[1][2][3] In 1861, Patterson opened a recruitment office at Contoocook and managed to enlist enough men to form a company of the 2nd New Hampshire Infantry Regiment.

[1][3][5] Around this time, Patterson was given command of the Third Brigade of the First Division of the XVIII Corps and went on to participate at the Battle of Fair Oaks & Darbytown Road.

[5][6] Patterson was promoted to full colonel on January 10, 1865, and brevetted brigadier general on March 3, 1865, before being honorably mustered out in December 1865.

[3][4] A Republican, Patterson was a member of the Sons of the American Revolution, the Wonalancet Club, the Grand Army of the Republic, and the Knights Templar.

[1][4] Patterson died at his home in Concord, New Hampshire, on July 18, 1923, and was buried at the Blossom Hill and Calvary Cemeteries.