 Complete the following phrase:  Under heavy German diplomatic pressure, Prince Paul had Yugoslavia join the Tripartite Pact on 25 March 1941, but with a proviso that Yugoslavia would not grant transit rights to the Wehrmacht to attack Greece. As the Metaxas Line protected the GreekBulgarian border, the Wehrmacht generals much preferred the idea of attacking Greece via Yugoslavia instead of Bulgaria. During a hasty meeting of Hitlers staff after the unexpected 27 March 