Giving into an aggressor in order to avoid a larger conflict

It sounds like you are describing the process of appeasement. Appeasement (giving into an aggressor's demands to avoid larger conflict) became infamous during the Munich Conference in the 1930s. The issue discussed at the Conference was Hitler's attempt to annex the Sudetenland from Czechoslovakia (against their will). Neville Chamberlain, the British Prime Minister, understood that Hitler had the potential to throw the continent back into war and thus approved the annexation (appeasing Hitler) in order to avoid larger conflict.