German and Italian submarines sank 36 Brazilian merchant ships resulting in 1,691 drownings and 1,079 other casualties. The sinkings led the Brazilian government into declaring war against the Axis when it announced at the Pan American States Conference in Rio on 28 January 1942, its decision to sever diplomatic relations with Germany, Japan, and Italy.

On 2 July 1944, the first five thousand Brazilian Expeditionary Force soldiers left Brazil for Europe aboard the USNS GENERAL MANN and arrived in Italy on 16 July. They disembarked in Naples, where they waited to join US Task Force 45.