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Britain
Allies Of Great Britain. Britain and Belgium had a treaty to support each other if they were attacked. in 1914, Germany attacked France by moving through Belgium. Britain told Germany to retreat. -
United States
Up to that date, America had tried to keep out of World War One – though she had traded with nations involved in the war – but unrestricted submarine warfare, introduced by the Germans on January 9th, 1917, was the primary issue that caused Woodrow Wilson to ask Congress to declare war on Germany on April 2nd. -
Russia
Russian entry into World War I. Russia entered into World War I on August 1, 1914, when Germany declared war on it. -
France
France was bound by treaty to defend Russia.