Colonel Rudolphus Ritzema was an American officer in the New York Line during the American Revolutionary War, and later changed sides, serving as a lieutenant colonel in a British regiment.
On June 30, 1775, Ritzema was appointed lieutenant colonel of the 1st New York Regiment. In July he seized British armaments in New York City. On November 28, 1775 he was appointed colonel of the 3rd New York Regiment on the recommendation of General Richard Montgomery accompanied Benedict Arnold to Quebec.
After the retreat from Quebec, his regiment was assigned to the defense of New York, and placed in Lord Stirling’s brigade. According to charges filed by Stirling, Ritzema was lax in maintaining order and discipline in his regiment, which was two hours late for a parade review on July 1, 1776. Stirling placed Ritzema on report, in response to which Ritzema is alleged to have used disrespectful language. While he was subjected to a court martial over the slight, Ritzema was cleared when Stirling chose to overlook the slight.
The bad blood appears to have continued, and during the Battle of White Plains, Ritzema deserted and joined the British Army. In May 1778, as a lieutenant colonel in the British army, he raised a few companies of an organization called the Royal American Reformers.