The invasion of Yugoslavia is also known as the April War. The order for the invasion was put forward in "Führer Directive No. 25", which Adolf Hitler issued on 27 March 1941. The country was overwhelmed and as soon as April 17, 1941 the Royal Yugoslav Army submitted their unconditional surrender.
Greece only held out a little longer. German troops raised the Nazi flag in Athens at the end of April, 1941.