Pieter van der Does was born in Leiden. In 1586 he became superintendent of the Dutch fleet which witnessed the defeat of the Spanish Armada two years later. In 1588 he was wounded at the siege of Geertruidenberg. In 1587 he was also bailiff and dijkgraaf of the Rijnland water board, and in 1588 chief schout of Leiden. On 23 December 1588 he received the post of vice-admiral of west Holland, and some time later he was also master-general of the artillery. In 1594 he was wounded during the siege of Groningen. For his services the States of Holland and West Friesland granted him the fiefdoms of Vriesekoop and Rijnsaterwoude and the title of jonkheer.