POA2 Master Rules and Barrage supplement (1904 - 1935), and Characterization Deck.

BARRAGE covers:
Russo-Japanese War 1904-1905
World War I 1914-1918 (All Fronts)
Russian Civil War 1918-1921
Russo-Polish War 1919-1920
Other Wars in this era that could use the basic BARRAGE rules:
Balkan Wars of 1912-1913
Greco-Turkish Wars of the 1920s
Chinese Warlord period of the 1920s and 1930s
Scale:
1" = 25 yards
1 infantry unit is a company (4 stands)
1 cavalry unit is a squadron (4 stands)
1 Machine-gun unit is a Machine-gun section or platoon (1 stand – representing 2 Machine guns)
1 Artillery unit is a battery (2 stands per battery – 2-3 guns per stand)
1 Tank or Armored Car unit is 2-3 vehicles (represented by 1 model)
1 turn = 15 minutes