Sumner Sewall demonstrated a robust commitment to public service and leadership from a young age. He interrupted his education to serve in World War I, where he distinguished himself as a fighter pilot. Post-war, Sewall transitioned into executive roles in the aviation industry before entering local politics. He served in the Maine state legislature and later as governor, where he implemented significant reforms. Sewall also held leadership positions in the private sector and military administration.

Sumner Sewall's political career is marked by a blend of military valor and pragmatic governance, with a penchant for surprising alliances. His military accolades contrast with a legislative record that often defies partisan lines, suggesting an ideologically agile approach. His tenure as governor saw progressive labor reforms, yet his later political ambitions were thwarted by unexpected electoral outcomes.