No doubt Adolf Hitler was in an unusually good mood as he celebrated his 110th birthday in the celestial realm of Valhalla on April 20, 1999.

Germans are again engaged in warfare. German aircraft are again dropping bombs and firing missiles at the hated Serbs - the people who perhaps contributed more to the defeat of the German dictator than any other people of comparable numbers and resources.

No doubt Herr Hitler has often reflected on what might have happened if Yugoslavia had joined the Axis powers as it was scheduled to do before the change in government that gave Yugoslavia a government that opposed fascism and all of its works.

If Yugoslavia had joined the Axis powers there would have been no invasion of Yugoslavia by Germany. The invasion of the Soviet Union could have taken place a month early. As it happened, the Germans were obliged to spend a month in a military campaign which defeated the regular Yugoslav armed forces.

If the Russian campaign had occured a month earlier, Hitler's Wehrmacht might have conquered Russia as General Winter would have arrived too late to do the Soviets any good. But Yugoslavia resisted Hitler and gave the Soviets the month that allowed them and General Winter to stop the German invasion dead in its tracks.

And then Herr Hitler no doubt wondered how he could have used those 200,000 troops he had to keep in Yugo- slavia to fight Tito's partisans and Michailovitch's Chetniks. They undoubtedly could have been used decisively on many battlefields - instead they were bogged down in Yugoslavia barely holding their own against the guerrillas.

But vengeance is sweet. The German warlord has now had a happy 110th birthday courtesy of the grand American warlord residing at 1600 Pennsylvania Avenue and the petty warlords constituting his 18 European allies.