In 1941, he commanded a battalion of Ustaše Militia that committed many war crimes and atrocities on civilians during the Genocide of Serbs in the Independent State of Croatia.

After being involved in an assassination attempt on Home Guard general Ivan Prpić in 1943, Herenčić had to emigrate to Hungary.

Ivo Herenčić was born on 28 February 1910 in Bjelovar, a city in the Kingdom of Croatia-Slavonia, a part of the Austro-Hungarian Empire.

In the early 1930s, Herenčić was a member of the security detail for the leader of the Croatian Peasant Party, Vladko Maček.

[1] In 1933, Herenčić left Yugoslavia and on 9 September he joined a camp for members of the ultra-nationalist and fascist Ustaše organisation in Borgo Val di Taro, Italy.

Oreb and Herenčić traveled to Klagenfurt in Austria using fake passports in the names of Emil Benedikt and Janoš Kren respectively.

Oreb was in the crowd and had two hand grenades in his pockets which he had been taught how to throw in a training camp in Vischetto [sh].

Podgorelac and Begović were taken into custody where they gave a detailed description of Oreb, who was caught by the police the same day, in Velika Gorica.

[11][12] In 1935, he became the commander of the 1st Ustaše Company, a paramilitary unit with a strength of 74 men, stationed on the Italian island of Lipari.

The following morning Pavelić tasked Herenčić with traveling to Zagreb where he was supposed to meet with the Ustaše deputy leader, Slavko Kvaternik.

[16] After Pavelić arrived in Zagreb, he sent Herenčić along with Jure Francetić and Mijo Babić to Bosnia and Herzegovina to form Ustaše units and organizations.

After this, the battalion traveled to the German occupation zone, where it continued to commit atrocities that disgusted even the high-ranking officials of the NDH.

[24] In mid-December 1944, Herenčić was promoted to the rank of general[25] and in mid-March 1945, he was appointed commander of the newly formed 5th Ustaše Corps.

[26] Herenčić, along with two other generals, Vladimir Metikoš and Vjekoslav Servatzy, led the withdrawal of the Croatian Armed Forces towards Austria with the goal of surrendering to the advancing British.

[27] Once the lead elements of the fleeing columns reached Bleiburg just across the Austrian border on 14 May 1945 they were stopped by the British 38th (Irish) Brigade, commanded by Brigadier Patrick T.D.

[28][29] Although he was not able to negotiate passage for the NDH forces and the accompanying civilians into Austria, Herenčić himself was able to escape into the countryside and make his way to Italy.