Until the advent of railways in the 19th century, goods and supplies were largely transported by water, making rivers such as the Lys, Sambre and Meuse vital for trade and military operations. The primary French objective in 1673 was the capture of Maastricht, which controlled a key access point on the Meuse; the city surrendered on 30 June. In June 1673, the French occupation of Kleve and lack of money temporarily drove Brandenburg-Prussia out of the war in the Peace of Vossem.