 Complete the following phrase:  On 25 March 1941, the government of regent Crown Prince Paul signed the Tripartite Pact, joining the Axis powers in an effort to stay out of the Second World War and keep Yugoslavia neutral during the conflict. This was immediately followed by mass protests in Belgrade and a military coup détat led by Air Force commander General Dušan Simović, who proclaimed King Peter II to be of age to rule the realm. As a result, the city was heavily bombed by the Luftwaffe on 6 April 1941, killing up to 2,274 people. Yugoslavia was then 