The correct answer is: German troops invaded France through Belgium on August 4th, 1914, as part of the Schlieffen Plan.
Not only had Britain promised to defend Belgium under the Treaty of London of 1839, moreover German control of Belgium would have been seen as a serious threat to Britain.
Belgium's ports were close to the British coast and German control of Belgium would have been seen as a serious threat to Britain. In the end, Britain refused to ignore the events of 4 August 1914, when Germany attacked France through Belgium. Within hours, Britain declared war on Germany.
Vietnamization of the war was the U.S. policy that required "South Vietnamese troops to replace American troops". The point of this was to ease frustration in the US that too many American soldiers were dying in a way many Americans felt was pointless.
