One of the aspects of wargame rules is the morale of the troops. How the troops feel is an important aspect of their willingness to the enemy. There are many aspects to morale and it can be difficult to quantify but when writing wargame rules I try to select rules that will cause the players to behave much like real solders and their commanders.
Troops need and want food, water, clothing, weapons, entertainment, and medical care for themselves and their animals. They miss their families and so they like mascots and mail to bring a little bit of home along with them. To simulate these factors I require units to have representations of these elements or suffer lowered morale. Lower morale as a practical matter in game terms means the soldiers do not fire a accurately due to fatigue, fear, hunger and other factors.
My battalions generally get at least one musician, one medical trooper, and one veterinary person if they have animals, food preparation staff, and an animal mascot, to provide the troops with a morale boost. I also include cobblers, armorers, and other service troops. Failure to have these troops will cause a drop in morale.