Gillis Thyssen Campen served the Admiralty of Amsterdam. Frank Fox says that Gillis Thyssen (Tijssen, Thijssen) Campen was Cornelis Tromp's Vice-Admiral at the Battle of Lowestoft, in 1665. He says that at the Battle of Lowestoft, four ships had run together and were tangled. They were Gillis Thyssen Campen's flagship, the Koevorden (56 guns), the Prins Maurits (53 guns), the Elf Steden (54 guns), and the Stad Utrecht (48 guns). They would not surrender to the English, so a fireship was sent in. One ship blew up, and freed the Elf Steden, which was towed off by another Dutch ship. Gillis Thyssen Campen was killed in the explosion.
At the start of the First Anglo-Dutch War, Gillis Thyssen Campen commanded the 24-guns hired ship, the Gouden Leeuw. In October 1652, she was paid off, along with other older and smaller hired ships. By early 1653, he was given the 42-gun ship, the Groningen, which he commanded for the rest of the war.