1 January 1945: A soldier of the 399th Infantry Regiment looks after his feet in the midst of battle. An infantryman's feet are the most vulnerable and most difficult to maintain part of his body in combat. The shoe-pacs issued to the soldiers of the 100th Infantry Division just before their entry into combat were ideal for troops who were relatively stationary, such as those assigned to headquarters units, but they had serious limitations for wear by combat infantrymen. While the insulation and waterproofing made them much more comfortable than shoes and leggings, they also sealed in sweat…and infantrymen's feet do a great deal of sweating during routine combat operations. Thus, as uncomfortable as it was in the snow of the most bitter winter in western Europe of the 20th century to that point, removing the shoe-pacs, drying bare feet, and exchanging wet socks for dry ones were absolutely critical. If not done, a painful condition called "immersion foot," involving cracked and split skin, could easily develop; in worse cases, "trench foot," involving extremely serious infection, might be the penalty for failing to conduct effective maintenance on "the M1 foot."ce.