I read that in Normandy in 1944, the US Army 90th division lost an average of 48% of its lieutenants every week, and that the infantry alone required 36,000 officer replacements every month in the ETO. Just why is it these losses were so disproportionately high compared to enlisted personnel?
A couple of reasons.
Firstly, the philosophy of 'lead from the front'. Note that unlike other armies which usually have platoon commanders, the US army has platoon -leaders-. The US Army's infantry motto is "Follow Me" and epitomises the attitude troops are supposed to show, and the officers in particular are supposed to show it. That's not to mean that the LT is supposed to be the front guy in the stick every time, but he's going to get stuck in there more than most new guys.
The second problem is that the LT is usually new. Unlike enlisted, of which there are many in a platoon, there's only one officer, and the chances are he's new. After all, it's the first rank of officer. As a result, of all the LTs in the Army, there is a vast proportion of inexperience as compared to of all the enlisted, a number of whom have learned how to survive on the battlefield.
Honestly, though, I'm not sure what the proportion of casualties per enlisted personnel actually are, but if they are higher, the above are good reasons as to why.
infantry alone required 36,000 officer replacements every month in the ETO.
I'm going to ask for a source on this. In all of WW2, the US had about 420,000 people killed, and another 670,000 wounded, or 1,090,000 people injured or killed total, across all theaters. Even if 36,000 is accurate and from DDAY until the end of European operations, that's still 10-11 months, 360,000-396,000 officers replaced.
Is that number accurate, and what are the time frames?