What invasion during World War 2 inflicted the most US casualties?

Answer 1

If you mean which parts of the army, it probably would be The Marines.

Other wise for divisions, it might be The 1st Infantry Division, 29th Infantry Division, 4th Infantry Division, 90th Infantry Division, and many other divisions.

Answer 2

The question needs to be qualified. For example, do you mean in total deaths regardless how long the duration of a particular battle, or by the ratio of casualties per total combatants. Here is one answer,the fight at BETIO , TARAWA LAGOON, cost more American lives per total combatants per square yards per hours fighting than probably any other designated landing. But there were other fights that were as fierce and smaller or larger in scope. The struggle going up the boot from south Italy was costly. The deaths from ship sinkings by submarines was also severe. By size of square yards BETIO is reputed to be the most heavily defended site. However, every battle I have studied was difficult, traumatic, fearsome,painful and sad. Darryll Salvadori staceysmail@att.net

Answer 3

The Battle of the Bulge with 19,275 killed. There were also 23,554 missing or taken prisoner. By comparison, 3,393 were killed on D-Day, 7,000 died at Iwo Jima and 12,000 died on Okinawa.