George William Lay was born around 1822 in Virginia. He graduated from West Point in 1842 and joined the United States Army. He served with the Meteorological Bureau from 1843 until 1845, and he took part in the Mexican-American War. He was promoted to 1st lieutenant in April 1851 and then to captain in December 1856. In July 1855, he married Henrietta Campbell, the daughter of Supreme Court justice John A. Campbell. He served on General Winfield Scott’s staff from 1854 until March 1861.
He resigned on March 2, 1861. The following month, he became superintendent of Louisiana State Seminar of Learning & Military Academy (present-day Louisiana State University). He left the seminar soon afterward to join the Confederate army. During the war, he served on the staffs of General Milledge Bonham and General Joseph E. Johnston. He worked in the Confederate Conscription Bureau from January 1863 until the end of the war.
He died in New Orleans, Louisiana, on May 7, 1867.