[2] In the spring of 1864 the gang rode from Belt's rancho over to Santa Clara County, a center of Copperhead sympathizers, to recruit more members.
[3] By October, 1864, with the presidential election approaching and the Civil War in the East reaching a climax, Mason and Henry's gang quickly deteriorated into brigands but because they called themselves Confederate soldiers, they managed to have support among the Copperheads in the area.
These crimes were described in the Stockton Daily Independent, for Monday, 14 November 1864: On the evening after the election MASON and McHENRY went over to Dutch Charley's, against whom they had a spite, and killed him.
Mason was described by The Visalia 'Delta' of November 30, 1864 as one of two secession guerillas and murderers: "who killed ROBINSON and 2 other men the day after the late Presidential election: JOHN MASON - Thick set man; about 5 feet 7 inches in height; weight, 165 or 170 pounds; age 30 or 32 years; limps one leg, and has a rocking walk; scar on 1 cheek; hair light color and very long; has it cut short underneath, so that he can tuck it up and give it the appearance of being short; small whiskers on the chin, redish color; small blue eyes, and have rather a glassy appearance; high, broad cheek bones.
While in hiding, the gang frequented Watsonville where the local secessionists continued to shelter them as they made periodic raids up and down the San Joaquin Valley.
[6] They held up a stage on the road from Watsonville to Visalia, killing three men and vowing to "slay every Republican they would meet."
[7] In April 1865, word arrived at San Juan that the Mason Henry Gang had attacked at Firebaugh's Ferry.
Captain Jimeno, in command of Camp Low, sent Lieutenant John Lafferty and a detachment of five Californio lancers from Company B, 1st Battalion of Native Cavalry, California Volunteers, in pursuit of the bandits.
Hoping to cut off the gang at Panoche Pass, the lancers rode south along the western flank of the Diablo Range and encountered Mason the next morning.
As the bandit spurred his horse in a desperate attempt to escape, Lafferty fired, wounding Mason in the hip and felling his mount with a single bullet.
[8] When the Civil War ended in April with Lee's surrender at Appomattox and no longer shielded by "the cause", the gang came under pressure in Central California.
That night while the three were in the same house, none went to sleep but in the early morning Mason lay down on his bed under a blanket, but was awake.