As a member of the Council of State (which was the most important executive organ of the Republic in the military field, especially after the Second Stadtholderless Period had started) he became a "gedeputeerde te velde" for Friesland at the headquarters of the Duke of Marlborough from 1706 until the Duke's dismissal in 1711. As such he was charged with advising the Duke, and with keeping an eye on him, as agreed when Marlborough was made lieutenant-captain-general of the army of the Republic in 1702. The Dutch deputies-in-the-field had the right to veto the Duke's tactical decisions if they thought the interests of the Republic demanded it, and this had led to much friction with Marlborough in previous years. Goslinga, however, proved cooperative generally and managed to provide a positive contribution during the battles of Ramillies, Oudenaarde, and Malplaquet.