WW1 - ④ Part Four : Prolonged war • 22 Feb 2025 World War I - The Fourth Story Prolonged war <Mitrailleuse Vickers> During this period, the widespread use of machine guns became a significant factor in the war. Previously, soldiers used s… Allied CooperationGermany Resource ShortageHistory&KeyeventsMachine GunsPoison GasSubmarinesTanksTrench WarfareUnrestricted Submarine WarfareUS Entry into WWIWorld War I