countries and maps of Battlefield 1

Kingdom of Belgium
It is interesting that Belgium has 5 maps in the Battlefield 1918 mod (Battle of Halen, Battle of Liège, Battle of the Nete, Siege of Antwerp, Ramskapelle/Battle of the Yser).
And these battles were in the very first few months of the First World War in 1914.

Battle of Halen
https://en.wikipedia.org/wiki/Battle_of_Halen
The Battle of Halen, also known as the Battle of the Silver Helmets because of the many cavalry helmets left behind on the battlefield by the German cuirassiers, took place on 12 August 1914 at the beginning of the First World War, between German forces led by Georg von der Marwitz and Belgian troops led by Léon De Witte. The battle was a Belgian tactical victory but did little to delay the German invasion of Belgium.

Battle of Liège
https://en.wikipedia.org/wiki/Li%C3%A8ge
Liège's fortifications were redesigned by Henri Alexis Brialmont in the 1880s and a chain of twelve forts was constructed around the city to provide defence in depth. This presented a major obstacle to the Imperial German Army in 1914, whose Schlieffen Plan relied on being able to quickly pass through the Meuse valley and the Ardennes en route to France. The German invasion of Belgium on 5 August 1914 soon reached Liège, which was defended by 30,000 troops under General Gérard Leman in the Battle of Liège. The forts initially held off General Alexander von Kluck's German First Army of about 100,000 men but were pulverised into submission by a five-day bombardment by heavy artillery, including thirty-two 21 cm mortars and two German 42 cm Big Bertha howitzers. Due to faulty planning of the protection of the underground defence tunnels beneath the main citadel, one direct artillery hit caused a huge explosion, which eventually led to the surrender of the Belgian forces.

Battle of the Nete
https://bf1918.fandom.com/wiki/Battle_of_the_Nete
Battle of the Nete was part of Siege of northern Belgian city of Antwerp, took place in September-October 1914. Nete is small canal dug out 10-15 kilometres southeast of Antwerp, between two lines of defense forts.

Siege of Antwerp
https://en.wikipedia.org/wiki/Antwerp
During World War I, the city became the fallback point of the Belgian Army after the defeat at Liège. The Siege of Antwerp lasted for 11 days, but the city was taken after heavy fighting by the German Army, and the Belgians were forced to retreat westwards.

Ramskapelle (Battle of the Yser)
https://en.wikipedia.org/wiki/Battle_of_the_Yser
The Battle of the Yser was a battle of the First World War that took place in October 1914 between the towns of Nieuwpoort and Diksmuide, along a 35 km (22 mi) stretch of the Yser River and the Yperlee Canal, in Belgium. The front line was held by a large Belgian force, which halted the German advance in a costly defensive battle. On 25 October, the German pressure on the Belgians was so great that a decision was taken to inundate the Belgian front line. After an abortive attempt on 21 October, the Belgians managed to open the sluices at Nieuwpoort during the nights of 26–30 October, during high tides, steadily raising the water level until an impassable flooded area was created of about one mi (2 km) wide, stretching as far south as Diksmuide.The Germans attacked again on the Yser front on 30 October, overran the Belgian second line and reached Ramskapelle and Pervijze. Belgian and French counter-attacks recovered Ramskapelle and the final attack, planned for the next day was called off when the Germans realised that the land behind them was flooding. The Germans withdrew in the night of 30/31 October.

Here is the link to the "List of infantry weapons of World War I (Kingdom of Belgium)"
https://en.wikipedia.org/wiki/List_of_infantry_weapons_of_World_War_I#Kingdom_of_Belgium
According to wiki, the First World War Belgian standard issue rifle was the Mauser Model 1889 (1889 Belgian Mauser).
And this Belgian Comblain falling-block rifle is very interesting.

The Belgian Minerva Armored Car could have been a new vehicle in the BF1 game.
https://en.wikipedia.org/wiki/Minerva_Armored_Car
The Minerva Armoured Car was a military armoured car expediently developed from Minerva civilian automobiles by Belgium at the start of the First World War. Before the Minerva factory was captured during the German invasion and occupation of Belgium about thirty Minerva armored cars were built. In 1916 the design of the original armoured car was completely revised. The open top was now fully enclosed and the machine gun under an armoured cupola. The Belgian Army used the cars as motorised cavalry units with three-car platoons. The armoured car units were mostly used for reconnaissance, infantry fire support and missions behind enemy lines. After the Western Front became bogged down in trench warfare some of the cars were sent to the Eastern Front with the Belgian Expeditionary Corps in Russia.

The BF1 youtuber "Flakfire" had a theory that DICE referred the new nations and new maps in some skin names, even before the DLC was released.

for example (where Flakfire's prediction was true):

-Achi Baba skin for No. 3 Revolver (BF1 base game weapon) -> later Achi Baba map is in the "Turning Tides" DLC
-Caporetto skin for Frommer Stop (BF1 base game weapon) -> later Caporetto map is in the last "Apocalypse" DLC
-Isonzo skin for Automatico M1918 (BF1 base game weapon) -> later Caporetto map is in the last "Apocalypse" DLC (the Battle of Caporetto is the Twelfth Battle of the Isonzo)
-Galícia skin for Gewehr M.95 (BF1 base game weapon) -> later Galicia map is in the "In the Name of the Tsars" DLC
-Somme skin for Auto Revolver (BF1 base game weapon) -> later River Somme map is in the last "Apocalypse" DLC
-The Selle skin for MP18 (BF1 base game weapon) -> later Giant's Shadow map (the map takes place during the Battle of the Selle) was released on Christmas 2016
-Vaux skin for Model 10-A (BF1 base game weapon) -> later Fort De Vaux map is in the French "They Shall Not Pass" DLC
-Verdun skin for M1909 Benét-Mercié (BF1 base game weapon) -> later Verdun Heights map is in the French "They Shall Not Pass" DLC

What skin names are in the BF1 game that can be connected to Belgium (these locations could have been potential Belgian DLC maps)?

-Charleroi skin for Selbstlader 1906 (BF1 base game weapon)
-Flanders skin for Artillery Truck (BF1 base game vehicle)
-In Flanders Fields skin for M1911 (BF1 base game weapon)
-Liège skin for Gewehr 98 (BF1 base game weapon)
-Messines skin for Lewis Gun (BF1 base game weapon)
-Poperinge skin for Ross MkIII (APOC DLC weapon)
-Ramscapelle skin for MP18 (BF1 base game weapon)
-St Eloi skin for Ross MkIII (APOC DLC weapon)
-The Hound of Mons skin for Selbstlader 1906 (BF1 base game weapon)
-Zonnebeke skin for Ross MkIII (APOC DLC weapon)
-Ypres skin for M1907 SL (BF1 base game weapon)

my tv-series recommendation for Belgium:
In Vlaamse Velden / In Flanders Fields (2014)
https://www.imdb.com/title/tt2253780/

This is a 10-part Belgian tv-series on the theme of the First World War, following the events in Belgium from 1914 to 1918 through a Belgian (Flemish) family. I think it has English subtitles.

Siege of Antwerp (1914)
On the night of 25/26 August, the city was bombed by a German Zeppelin airship.

Ramskapelle (Battle of the Yser)
The Germans attacked again on the Yser front on 30 October, overran the Belgian second line and reached Ramskapelle and Pervijze. Belgian and French counter-attacks recovered Ramskapelle and the final attack, planned for the next day was called off when the Germans realised that the land behind them was flooding. The Germans withdrew in the night of 30/31 October.

S1.E1 ∙ Juli - Augustus 1914
S1.E2 ∙ September - Oktober 1914
S1.E3 ∙ Oktober 1914
S1.E4 ∙ December 1914 - Juni 1915
S1.E5 ∙ Juni - September 1915
S1.E6 ∙ December 1915 - Oktober 1916
S1.E7 ∙ Oktober 1916 - April 1917
S1.E8 ∙ April 1917 - November 1917
S1.E9 ∙ December 1917 - Juni 1918
S1.E10 ∙ Juli - September 1918

https://www.youtube.com/watch?v=squQl5-fMDs

Empire of Japan

Japan also participated in World War I as a member of the Entente Powers/Allies.
In Battlefield 1, many skins have "Japan during World War I"-related names, for example:

-Battle of Tsingtao skins
The siege of Tsingtao was the attack on the German port of Qingdao (Tsingtao) during World War I by Japan and the United Kingdom. The siege was waged against Imperial Germany between 27 August and 7 November 1914. The siege was the first encounter between Japanese and German forces, the first Anglo-Japanese operation of the war, and the only major land battle in the Asian and Pacific theatre during World War I.

-Mitsuomi skin for Japanese Type 38 Arisaka
Kamio Mitsuomi (27 February 1856 – 6 February 1927) was a Japanese general in the Imperial Japanese Army, who commanded the Allied land forces during the Siege of Qingdao in World War I.

-Die Kaiserin Elizabeth for Gewehr M.95
-Farman skin for Autoloading 8
-Wakamiya skin for Japanese Type 38 Arisaka
From 5 September 1914, Wakamiya conducted the world's first naval-launched air raids during the first months of the First World War from Kiaochow Bay off Tsingtao, which is located in China. On 6 September 1914 a Farman aircraft launched by Wakamiya attacked the Austro-Hungarian cruiser Kaiserin Elisabeth and the German gunboat Jaguar in Qiaozhou Bay; neither ship was hit. Her seaplanes bombarded German-held land targets (communication centers and command centers) in the Qingdao peninsula of Shandong province and ships in Qiaozhou Bay from September to 6 November 1914, during the Siege of Tsingtao.

An interesting fact about Battle of Tsingtao on the BF1 loading screen:
German Pilot Gunther Plüschow downed a Japanese Airplane with his Luger Pistol, the first time a pilot ever shot down another plane. He was also the only German POW to escape Britain and make it back to Germany

Battlefield 1 has a Japanese Dog Tag named "Sakura":

In Battlefield 1918, the Siege of Tsingtao (1914) appears on two maps (Fort Bismarck and Tsingtao maps).

Tsingtao map

Fort Bismarck map
https://en.wikipedia.org/wiki/Siege_of_Tsingtao
The Boxer Rebellion, at the beginning of the century, had led Germany to consider the defence of Tsingtao. The port and the town were divided from the rest of the peninsula by steep hills. The main line of defence lay along three hills, Mount Moltke, Mount Bismarck, and Mount Iltis, from the Kaiserstuhl to Litsuner Heights. Guarding the left wing was Fort Moltke, on the hill of the same name, with two 9.4 in. (240 mm) guns. The heaviest firepower was concentrated in the four 11 in. (280 mm) howitzers of Fort Bismarck.

The fifth Japanese DLC could have included the following weapons:
-Type 3 heavy machine gun
https://en.wikipedia.org/wiki/Type_3_heavy_machine_gun
The Type 3 heavy machine gun, also known as the Taishō 14 machine gun, was a Japanese air-cooled heavy machine gun. The Type 3 heavy machine gun was in a long-line of Japanese Hotchkiss machine gun variants that the Imperial Japanese Army would utilize from 1901 to 1945. The Type 38 heavy machine gun would first see action in Tsingtao, China during World War I.

-Meiji Type 26 revolver
https://en.wikipedia.org/wiki/Type_26_revolver
The Type 26 or Model 26 "hammerless" revolver was the first modern revolver adopted by the Imperial Japanese Army. The revolver saw action in conflicts including the Russo-Japanese War, World War I and World War II.

Empire of Japan
It is interesting that a 1963 Japanese war film based about the Siege of Tsingtao.
I don't know if the movie is available with subtitles other than Japanese.
A character in the film is based on the of the real Gunther Plüschow.

Siege of Fort Bismarck
https://tohostudiopedia.fandom.com/wiki/Siege_of_Fort_Bismarck

Siege of Fort Bismarck (青島要塞爆撃命令, Chintao yôsai bakugeki meirei) is a 1963 Japanese war film directed by Kengo Furusawa and special effects work by Eiji Tsuburaya. The film is set in World War I, which is rare for a Japanese movie. Based on a real Siege of Tsingtao, it depicts a team of aviators (who are pilots for the Imperial Japanese Navy Air Service) are on a dangerous mission to destroy all German defense fortresses before the Allies could land their forces to occupied the port city. In overseas country like the United States and Europe, it was released under the title, "Siege of Fort Bismarck". In order to shoot the film, in addition to the elaborate two aircraft miniatures like the Farman MF.11 and the Etrich Taube with a wingspan of 1 meter or more, a full-scale model for shooting the main story with a propeller rotating was produced. In both cases, the filming was done in addition to the set, and on Mt. Fuji, it was hung from a helicopter. The full-scale model of the Farman MF.11 was assembled by a craftsman specializing in gliders by borrowing the actual machine in the disassembled state saved by the Japan Aeronautic Association and creating a restoration drawing. The Japanese seaplane carrier Wakamiya was also photographed using a cargo ship.

The Kingdom of Montenegro was also a belligerent in the First World War.
https://en.wikipedia.org/wiki/Allies_of_World_War_I
Fighting commenced when Austria invaded Serbia on 28 July 1914, purportedly in response to the assassination of Archduke Franz Ferdinand, heir to Emperor Franz Joseph I; this brought Serbia's ally Montenegro into the war on 8 August and it attacked the Austrian naval base at Cattaro, modern Kotor.

In Battlefield 1 i think there is only one skin name related to the Kingdom of Montenegro:
King Nicholas skin for Gasser M1870
Nicholas I of Montenegro
https://en.wikipedia.org/wiki/Nicholas_I_of_Montenegro
Nikola I Petrović-Njegoš (7 October 1841 – 1 March 1921) was the last monarch of Montenegro from 1860 to 1918, reigning as prince from 1860 to 1910 and as the country's first and only king from 1910 to 1918.

In BF1918, Montenegro is present on two maps of the Balkan front:

The Kingdom of Serbia would also have had a chance in the fifth expansion of Battlefield 1.

for example, codex entry related to Serbia:
Austria-Hungary (Codex Entry)
In 1908, Austria-Hungary had annexed Bosnia, making Serbia the next in line. And if Serbia fell, Russia would lose all influence in the Balkan region.

codex entry related to Serbia:
Women Rise (Codex Entry)
And indeed, some even fought at the front. Flora Sandes, Milunka Savic, Helen Ruz, Olga Kokovtseva and of course - the Russian Women's Battalion of Death, led by Maria Bocharevka.
Flora Sandes - https://en.wikipedia.org/wiki/Flora_Sandes
Milunka Savic - https://en.wikipedia.org/wiki/Milunka_Savi%C4%87

a fact related to Serbia on the loading screen:
Too young to be sentenced to death, the man who assassinated Franz Ferdinand was ineligible for the death penalty. Gavrilo Princip sat out most of the war while imprisoned. He died of tubercolosis in 1918.
Gavrilo Princip - https://en.wikipedia.org/wiki/Gavrilo_Princip

another fact about Serbia on the loading screen:
A Serbian artilleryman downed an enemy plane with a cannon in 1915, the first ground-to-air kill.
Radoje Ljutovac - https://en.wikipedia.org/wiki/Radoje_Ljutovac

another fact related to Serbia on the loading screen:
Momčilo Gavrić was, at eight years of age, the youngest soldier of the war. He joined a Serbian artillery division after his family was killed in 1914.
Momčilo Gavrić - https://en.wikipedia.org/wiki/Mom%C4%8Dilo_Gavri%C4%87

another fact about Serbia on the loading screen:
The Serbian Army retreated through the Albanian Alps after the Central Powers's invasion of Serbia in 1915. They reassembled on Corfu and were back in action in 1916.
Great Retreat (Serbia) - https://en.wikipedia.org/wiki/Great_Retreat_(Serbia)

Kingdom of Serbia

My movie recommendation:
King Petar the First (2018)
https://www.imdb.com/title/tt8161166/

Serbian film that shows the first part of the First World War (1914-1916) from the perspective of the Serbian king, Peter I.
This is a Serbian First World War themed movie, based on real events:
-Battle of Cer (15–24 August 1914) https://en.wikipedia.org/wiki/Battle_of_Cer
-Battle of Kolubara (16 November – 15 December 1914) https://en.wikipedia.org/wiki/Battle_of_Kolubara
-The Great Retreat (25 November 1915 – 18 January 1916) https://en.wikipedia.org/wiki/Great_Retreat_(Serbia)

The youngest Serbian WW1 soldier is also a character in the film:
Momčilo Gavrić - https://en.wikipedia.org/wiki/Mom%C4%8Dilo_Gavri%C4%87

Bulgaria
The Kingdom of Bulgaria was one of the Central Powers in World War I, and the last to join the alliance.

a fact related to Bulgaria on the loading screen:
The nation that mobilized the greatest percentage of its population in the war was Bulgaria.

another fact about Bulgaria on the loading screen:
Irish troops served not only on the Western Front, but even fought Bulgarians in the Balkans.

3 skins are associated with Bulgaria in Battlefield 1 (Monastir, Cobadin and Crna Bend skins)
-Monastir skin for Mosin-Nagant M91
During World War I Bitola (Monastir) was on the Salonica front. Bulgaria, a Central Power, took the city on 21 November 1915, while the Allied forces recaptured it in 1916. Bitola was divided into French, Russian, Italian and Serbian sections, under the command of French general Maurice Sarrail. Until Bulgaria's surrender in late autumn 1918, Bitola remained a front line city and was bombarded almost daily by air bombardment and artillery fire and was nearly destroyed.

-Cobadin skin for Mosin-Nagant M91
The First Battle of Cobadin was fought from 17 to 19 of September 1916 between the Bulgarian Third Army and the Romanian–Russian Army of the Dobruja. The Second Battle of Cobadin took place from 19 to 25 October 1916 between the Central Powers, chiefly the Bulgarian Third Army, and the Entente, represented by the Russo–Romanian Dobruja Army.

-Crna Bend skin for Vetterli-Vitali M1870/87
The Battle of the Cerna bend (1916) was a two-month-long battle between the Bulgarian and the Entente armies. The battle took place in the Macedonian front during the First World War Allied Monastir Offensive in October and November 1916.

Bulgaria participates in 6 Battlefield 1918's maps:
-Albania, October 1915 (Serbia vs Bulgaria)
-Battle of Bazargic, September 1916 (Serbia vs Bulgaria)
-Battle of Struga, November 1915 (Serbia vs Bulgaria)
-Hill 1050, May 1917 (Italy vs Bulgaria)
-Kosovo, November 1915 (Serbia vs Bulgaria)
-Morava Offensive, October 1915 (Serbia vs Bulgaria)

my ww1 movie recommendation with Bulgaria or the BF1 Crossbow Grenade Launcher's cameo role
Capitaine Conan (1996)
https://www.imfdb.org/wiki/Capitaine_Conan
Capitiane Conan is a 1996 French war drama movie directed by Bertrand Tavernier based on the 1934 novel of the same name by Roger Vercel. In September 1918, for four years the First World War raging in Europe coming to an end. In the Balkans, the Bulgarians allied with the German Empire and the Allies deliver tough battles (Macedonian Front). In the last battle before the surrender of Bulgaria the Sokol massif is stormed by the Allies and Captain Conan and his fifty comrades, mostly ex-prisoners from military prisons, have played a decisive role. This is a special unit in the regular army hierarchy, which operates according to its own ruthless rules.

Crossbow Grenade Launcher (Captain Conan)
https://www.youtube.com/watch?v=6xd770k7u6g

Kingdom of Romania
Romania allied with the Entente Powers during World War I.

there is a reference to Romania in the Fedorov Avtomat's Codex Entry:
The Russian Army adopted the Fedorov Avtomat in 1916, and it was first used in combat on the Romanian front, for example by a special unit of the 189th Izmail infantry regiment which were armed with 45 of the 6.5mm Fedorov Avtomats, and 8 of the earlier 7.62mm self-loading rifles.

3 skins are associated with Romania in Battlefield 1 (Marasti, Oituz and Hohenzollern skins)
-Marasti skin for Fedorov Avtomat
The Battle of Mărăști (Romanian: Bătălia de la Mărăști) was one of the main battles to take place on Romanian soil in World War I. It was fought between 22 July and 1 August 1917, and was an offensive operation of the Romanian and Russian armies intended to encircle and destroy the German 9th Army. According to General Alexandru Averescu, the commander of the Romanian Second Army at this major engagement, the Battle of Mărăști was the "first true victory in the history of the modern Romanian Army".

-Oituz skin for Fedorov Avtomat
The Battle of Oituz may refer to any of the following battles between Austro-Hungarian and German forces against Romanian ones during World War I:
First Battle of Oituz, 12–27 October 1916
Second Battle of Oituz, 10–16 November 1916
Third Battle of Oituz, 8–22 August 1917

-Hohenzollern skin for lMG 08/18
https://en.wikipedia.org/wiki/Ferdinand_I_of_Romania
Ferdinand I (Ferdinand Viktor Albert Meinrad; 24 August 1865 – 20 July 1927), nicknamed Întregitorul ("the Unifier"), was King of Romania from 1914 until his death in 1927. His family was part of the Catholic branch of the Prussian royal family Hohenzollern. Ferdinand became King of Romania on 10 October 1914, under the name Ferdinand I, following the death of his uncle, King Carol I. He ruled Romania during World War I, choosing to side with the Triple Entente against the Central Powers. This led to Kaiser Wilhelm II of Germany removing his name from the royal house of Hohenzollern.

Romania can be found on a Battlefield 1918 map:
-Transylvania, August 1916 (Romania vs Austria-Hungary)
https://en.wikipedia.org/wiki/Battle_of_Transylvania
The Battle of Transylvania was the first major operation of Romania during World War I, beginning on 27 August 1916. It started as an attempt by the Romanian Army to seize Transylvania, and potentially knock Austria-Hungary out of the war. Although initially successful, the offensive was brought to a halt after Bulgaria's attack on Dobruja. Coupled with a successful German and Austro-Hungarian counterattack which started in mid-September, the Romanian Army was eventually forced to retreat back to the Carpathians by mid-October.

a very special Romanian World War I weapon:
Fahrpanzer
https://en.wikipedia.org/wiki/Fahrpanzer#Romanian_infantry_variant
The Fahrpanzer was a mobile artillery piece made prior to World War I in Germany, implemented in several German fortifications from 1890 onwards and exported to several foreign military powers prior to the outbreak of hostilities. Romanian infantry variant: Romania purchased 334 Gruson Fahrpanzers, in the 53 mm caliber. These guns remained in their emplacements for about twenty years, before being transformed into infantry guns between 1914 and 1916 by mounting them on Romanian-built gun carriages. A few were transformed into anti-aircraft guns.

the BF1 loading screen has this historical fact:
Austria-Hungary issued recruitment posters in 15 different languages

I recommend the following World War I Romanian film to watch:
Forest of the Hanged (novel)
https://en.wikipedia.org/wiki/Forest_of_the_Hanged_(novel)
Forest of the Hanged (Romanian: Pădurea spânzuraților) is a novel by Romanian writer Liviu Rebreanu. Published in 1922, it is partly inspired by the experience of his brother Emil Rebreanu, an officer in the Austro-Hungarian Army hanged for espionage and desertion in 1917, during World War I. The novel was made into a film in 1965. The film was directed by Liviu Ciulei, who won the award for Best Director at the 1965 Cannes Film Festival. Plot: The protagonist is Lieutenant Apostol Bologa, who was born and raised in Parva - then Párva, Beszterce-Naszód County, Transylvania, Kingdom of Hungary. Although he was enrolled in the Philosophy Faculty of the University of Budapest, and he had not been conscripted into the army since he was a widow's son, Bologa volunteers into the Austro-Hungarian Army at the start of World War I. After attending artillery school, he is sent to the front. He fights valiantly in Italy and Galicia; wounded twice in the next two years, he is promoted to the rank of lieutenant and decorated three times. Sent on the Romanian front, in the Eastern Carpathians, the thought of desertion becomes an obsession for him.
https://www.youtube.com/watch?v=7aWbJ-H5e8o