Croat commanders of the army helped the Germans easily capture the Serbian soldiers and send them to jails. A Canadian Serb spoke of how his grandfather, stationed in Macedonia, was betrayed by the Croat commander, who subsequently, after the Germans took control of his men, departed in a small plane provided by the Germans.
This is what Ruth Mitchell, an American spy, who was even imprisoned for a while in a Gestapo prison in Belgrade during the war, writes:
The Croats, watching the rising power of Germany, decided to do business with Hitler. Secret agreements were arrived at and the Croat politicians understood that Germany would back them. After Hitler annexed Czechoslovakia in 1939, Dr. Machek, leader of the Croat Peasant Party, decided the time was ripe to take the first step toward independence. He demanded complete internal autonomy for Croatia "within the confines of the Yugoslav State." The request was granted by Prince Paul with the support of many of the Serb elements who, forthright and direct themselves, were tired of the inveterate Croat agitation and subversion.On April 10 the German troops marched into the city of Zagreb, in Croatia proper, and were greeted by the wildly enthusiastic cheers of a people who only twenty-three years before had received their Serb "brothers" and "liberators" in exactly the same way. Dr. Machek, who had carried on the intrigues with Germany, gave orders on the radio to all his followers to cooperate with the Axis.
The principal reason why Yugoslavia collapsed so quickly is that every Serbian officer had momentarily to expect to be shot in the back by his Croatian soldiers, and hundreds were so shot.
A total of 1,679 officers representing 95% of the Croat officers in the Yugoslav Army, who had sworn to protect their king and the country, proved traitors to their oath and went over to the enemy. The detailed figures, as given by the official gazette of the Independent State of Croatia, include 11 generals, 4 admirals, 52 colonels, 73 lieutenant colonels, 68 captains, and 72 naval captains and officers; also 1,342 non-commissioned officers, aviation specialists, and mechanics. Letters have been published in Croat papers in which Croat officers of high rank with the most cynical brutality BRAGGED that they had married Serbian girls of influential family with the single purpose of getting themselves into key positions for more effective treachery: so long and so well had the thing been planned.
Of 224,000 Yugoslav prisoners of war taken into Germany, less than 2% were Croats, and to them honor, for they only had to announce that they were Croats to be released at once. Of the 14,000 Serb officers who, if they agreed to submit to Germany, were offered their freedom to return home to their families, only 800 accepted, and most of them have been retaken and killed."
http://www.srpska-mreza.com/library/facts/mitchell.html
She was an American citizen who volunteered for the Chetniks.
There were certainly Croats, plenty of them, who were more than happy to become fascists and German clients.
But the Croats never voted any fascists into power.
I am as skeptical of Serbian website accounts of Croat malfeasance as I am skeptical of Croat website accounts of Serb malfeasance.
Both sides are so embittered I cannot take anything one says about the other at face value.
The truth will out.
It is bit ironic to criticize Croatia, just when in Serbia The Radical Party (chetniks-fascists) won the elections on Sunday.