[Simon Cameron, Sec. of War] Revised Regulations for the Army of the United States, 1861. Philadelphia: J.B. Lippincott & Co., 1861. 8vo, green embossed cloth, 559pp plus 6pp ads. On front pastedown and on lower page edges "Richard Penn Smith 1st. Lieutenant Company 'F' California Regiment" and "Lieut. R. Penn Smith Co. 'F' Bakers California Regt." 

[Simon Cameron, Sec. of War] Revised United States Army Regulations of 1861. With an Appendix containing the Changes and laws affecting Army Regulations and Articles of War to June 25, 1863. Washington: GPO, 1863. 8vo, blue embossed cloth, gilt spine lettering, 594pp. On front pastedown "Adjutants Office 71st Regt. Pa. Vols. Oct. 23, 1863." 

Shortly after the surrender of Fort Sumter, Senator Edward Baker of Oregon, close friend of Abraham Lincoln, got permission to recruit a regiment. Hundreds of men from Pennsylvania and New York City found themselves training along the streets of the Big Apple. This was the California Regiment, among the first three-year troops recruited. Initially, the unit was recognized by the Federal government, which was going to apply the enlisted men to the number to be recruited from California. In November, the unit suffered heavily at Balls Bluff and Edward Baker had been killed. Pennsylvania adopted the unit, which became the 71st Pennsylvania Volunteers, although many still referred to their unit as Baker's California Regiment. They went on to fight at Antietam, Marye's Heights (Fredericksburg), Gettysburg, and all of the subsequent Army of the Potomac battles. Of the 2200 men who enrolled, only 153 returned to Philadelphia to be mustered out.

R. Penn Smith was commissioned as 1st lieutenant in May 1861, promoted to adjutant in February 1862, major in November 1862 and colonel in May 1863. He was one of the few to muster out in July 1864.