At the start of the American Civil War, then Colonel Delafield helped equip and send volunteers from New York to the Union Army.

Delafield served as assistant engineer in the construction of Hampton Roads defenses from 1819 to 1824 and was in charge of fortifications and surveys in the Mississippi River delta area in 1824–1832.

Commissioned a major of engineers in July 1838, he was appointed superintendent of the Military Academy after the fire of 1838 and served till 1845.

[7] The book was suppressed during the American Civil War due to fears that it would be instructive to Confederate engineers as it contained multiple drawings and descriptions of military fortifications.

In the beginning of the Civil War he advised the governor of New York Edwin D. Morgan during the volunteer force creation.

Then, in 1861–1864, he was put in charge of New York Harbor defenses, including Governors Island and Fort at Sandy Hook.

[2] On March 8, 1866, President Andrew Johnson nominated Delafield for appointment to the grade of brevet major general in the Regular Army of the United States, to rank from March 13, 1865, and the United States Senate confirmed the appointment on May 4, 1866, and reconfirmed it due to a technicality on July 14, 1866.

In 1833 he married Harriet Baldwin Covington (1811–1894) with whom he had eight children, among them: This article contains public domain text from "Brigadier General Richard Delafield".