After the French campaign in 1522 ended and Frundsberg resigned from the leadership of the Landsknechts, he returned to lead the march of 6,000 men on upper Italy. A difficult alpine crossing through deep snow led to the Battle of Bicocca near Milan in April. Swiss nationals on foot fought alongside Frundsberg, who led and fought from the front. The emperor's victory at Bicocca allowed the return of the previous rulers of the oligarchic Republic of Genoa and the Duchy of Milan and brought the greater part of Lombardy under the influence of Charles V.