Commodore John Downes (December 23, 1784 – August 11, 1854) was an officer in the United States Navy, whose service covered the first half of the 19th century.

In March 1807, he was made a lieutenant and served as executive officer for Captain David Porter on the Essex during her cruise in the Pacific in the War of 1812.

He also participated in the action off Charles Island before sailing to Nuku Hiva to assist in building America's first military base in the Pacific.

Two days later the Epervier and three of the smaller vessels of the squadron captured the Algerine brig of war Estedio with twenty-two guns and 180 men off Cape Paios.

He so angered his associates, whom he kept busy counting money under poor conditions, that one of his midshipmen, William Rodgers, resigned from the Navy after coming ashore from this three-year voyage.

In February 1831, the American merchant ship arrived at the harbor of Quallah Battoo on the Pedir coast of Sumatra to take on a cargo of pepper.

They returned to Salem, the headquarters of much of America's trade with the East at that time, and also reported that the local chieftain denied any knowledge of the attack in his harbor.

If there was a regular government that Downes could deal with, he was authorized to negotiate with it, if not, he was to "inflict chastisement" on any "band of lawless pirates" responsible for the atrocity.

Downes, in command of the Potomac left New York harbor August 28, 1831 bound for Quallah Battoo by way of the Cape of Good Hope and the Indian Ocean.

[3] When Downes arrived at Valparaíso, Chile, Jeremiah N. Reynolds, an American explorer and author, joined the expedition as the commodore's private secretary for the trip and wrote a book about the experience, Voyage of the United States Frigate Potomac.

[citation needed] On returning home, Downes was severely criticized for his harsh actions, but Jackson supported him, saying the fighting would deter future aggression.