[3] On January 11, 1844, Foreman was married, to Lucinda Boothe (died 1880) and they had one daughter, Ann, and a son, Sands William.
His 3rd Regiment with Colonel Foreman in command was attached to the Army of Invasion of General Winfield Scott, and played a part in the siege of Veracruz, and in the march on Mexico City, Col Foreman's 3d Ill fought under General Shields at the battle of Cerro Gordo the 3d and 4th Ill "carried a battery of the enemy's on his extreme left (Santa Anna's), gain the national road and cut off his retreat route" (History of Illinois, Illinois in the Mexican War).
His regimental headquarters and several companies were sent from San Francisco to Camp Latham in Southern California in late 1861.
On May 2, 1862, General George Wright wrote to Colonel Ferris Foreman, the new commander of Camp Latham to send, two or three companies of the Second Cavalry with Lieutenant Colonel George S. Evans as commander to establish a post in the Owens Valley.
[7] Shortly afterward, Foreman's daughter Ann was discovered to have been in communication with the infamous secessionist and duelist Daniel Showalter who wrote her an affectionate letter that was found on the body of a Confederate spy in west Texas in September 1863.
He returned to California in his later years, and died in Stockton, San Joaquin County, February 11, 1901.