At the end of April 1945, during the retreat of German forces from northern Italy during the Allied Spring Offensive, Fretter-Pico's 148th Infantry Division was blocked by the Brazilian Expeditionary Force in the area of Collecchio-Fornovo di Taro while trying to gain the Po Valley. The 148th had remnants of the destroyed 90th Panzergrenadier Division and the RSI "Italia" Division tagging along but despite breakout attempts from 26–28 April, the Axis forces were surrounded and forced to surrender on 29 April 1945 in the Battle of Collecchio before General Heinrich von Vietinghoff's overall Axis surrender in Italy on 2 May. Generals Mario Carloni and Otto Fretter-Pico followed their 14,779 men into captivity, passing from Brazilian custody to a US POW camp some time later. He was released by US forces on July 7, 1948.