Born in Brown County, Ohio, his older brother was Jacob Ammen, who became a brigadier general in the Union Army. They both attended the same school as Ulysses S. Grant, who was best friends with Daniel. As children, Ammen rescued Grant from drowning.
Ammen entered the Navy as a midshipman on 7 July 1836. He served on Vandalia during 1838.
In February, 1852 Ammen was ordered to pick out a new location for the navy yard in California. He arrived in San Francisco around April 30, 1852 for that purpose.
In 1861–62, he commanded the gunboat Seneca in the South Atlantic Blockading Squadron. His bravery was conspicuous in the Battle of Port Royal, November 7, 1861. Later, under Samuel F. Dupont's command, he took part in all the operations on the coasts of Georgia and Florida. In the engagements with Fort McAllister, March 3, 1863, and with Fort Sumter, April 7, 1863, he commanded the monitor Patapsco. In the attacks on Fort Fisher, in December 1864, and January 1865, he was commissioned captain of the Mohican July 26, 1866.
He was promoted to Rear Admiral in 1877, and was retired June 4, 1878. Two years later, he wrote The American Inter-Oceanic Ship Canal Question. Afterwards he was a member of the board to locate the new Naval Observatory, and a representative of the United States at the Interoceanic Ship Canal Congress in Paris. He designed a cask balsa to facilitate the landing of troops and field artillery, a life-raft for steamers, and the steel ram Katahdin in 1893.
His publications include The Atlantic Coast in The Navy in the Civil War Series; Recollections of Grant; and The Old Navy and the New.
He died in Washington, D. C., and was buried at Arlington National Cemetery.
Two ships in the United States Navy have been named USS Ammen for him.
- (1901) Encyclopaedia of United States History
- This article includes text from the public domain Dictionary of American Naval Fighting Ships.