This is the 14723rd most frequent Russian word.
пехотой
"Пехотой" means "by infantry" or "infantry" in the instrumental case.
Here, 'пехоты' refers to a branch of the military specifically foot soldiers or infantry.
Войска состояли из кавалерии и пехоты.
The troops consisted of cavalry and infantry.
In this sentence, 'пехотой' indicates the presence of infantry as part of a moving column.
Перед нами двигалась колонна с пехотой.
A column of infantry was moving ahead of us.
Here, 'пехоты' signifies the specific army branch comprised of foot soldiers.