The Sicily Campaign had a major effect on World War II. It took a major Axis power of the war. Without Italy to worry about, the Allies were able to focus on defeating Germany.
In addition to that, there were many African-American fighters that distinguished themselves. The US Army brass was so impressed by how well they fought that they began to integrate the segregated divisions into integrated divisions. A battalion commander in the 78th division said that, “White men and colored men are welded together with a deep friendship and respect...When men undergo the same privations, face the same dangers, there can be no segregation.”
Overall, the Sicily Campaign had a positive impact on World War II for the Allies.