Which front during WW2 did American soldiers have the hardest time fighting?

I don't know statistically which was the most dangerous, but I think that many veterans regarded the fighting in the Pacific as especially fierce. There were a number of reasons for this. There were cultural differences in racial prejudices on both sides which led to dehumanization of the enemy and perhaps greater violence. American G eyes also believed at least that Japanese soldiers were especially reluctant to surrender and we're often believed to fight to the death more than German soldiers. Also, the fact that these were isolated islands with little or no population may have also encouraged more of a scorched-earth policy among the combatants.

Given the natural hazards of the tropics and the number of landings that took place I have to say the Pacific theater. That theater was fought mostly with Marines and they resent being called soldiers!

The fiercest fighting was in the Pacific, against the Japanese.

Note that in WW2, all "fronts" were much more mobile than the "Western Front" in WW1.

id say the pacific was harder for the marines . due to the horrible conditions in the jungles ,

Italy.

Being aircrew in a bomber over Europe was proportionally the most dangerous.