During the Russo-Swedish War of 1741–1743, Keith was briefly "de facto" Vice-Roy of Finland and responsible for the occupying Russian forces, James Keith convened the estates of southwestern Finland on 8 (or 18) September. He proved adept as a capable and liberal civil administrator. In late 1742, Keith was succeeded in the leadership of civil administration of Finland (now based at Turku) by the new Governor-General, Johannes Balthasar von Campenhausen.