Remaining at sea, Wainwright received orders to USS Connecticut, where he served during that ship's participation in the voyage of the Great White Fleet around the world from 1907 to 1909.

While leading a landing party from that ship in battle at Veracruz, Mexico, he earned the Medal of Honor for his outstanding conduct on April 21–22, 1914.

Lt. Wainwright was eminent and conspicuous in command of his battalion; was in the fighting of both days, and exhibited courage and skill in leading his men through action.

In seizing the customhouse, he encountered for many hours the heaviest and most pernicious concealed fire of the entire day, but his courage and coolness under trying conditions were marked.In September 1914, Wainwright detached from the Florida with orders to the Naval Academy.

[5] He died in Annapolis, Maryland March 28, 1944, and is buried in the United States Naval Academy Cemetery.