His discoveries resulted in a gold rush to the region, and this in turn led to the establishment of Arizona's first territorial capital at the mining town of Prescott.
A few months later he was drawn back to Arizona by the gold rush at Gila City, where he also worked for the Butterfield Overland Mail Company.
The Gila Rangers, with the support of warriors from the friendly Maricopa tribe, made a January 1860 expedition to the unexplored Bradshaw Mountains of central Arizona in pursuit of Apache raiders.
The expedition resulted in some noteworthy discoveries: the existence of the Hassayampa River and traces of mineral riches, including gold, in an area that appeared well-suited for ranching and farming.
When the Union Army withdrew from the New Mexico Territory at the beginning of the Civil War, the men of Pinos Altos formed a militia company they named the Arizona Guards for defense against Apache attack.
After a time spent defending against Apaches and acting as the de facto police force for the area around Pinos Altos, Swilling led a portion of the Arizona Guards that reinforced the garrison of Tucson in 1862.
He is believed to have commanded a party of rebels who burned Stanwix Station and skirmished with the Union Army's California Column there in March.
He was also involved in the noted incident at White's Mill at Casa Blanca, Arizona when Union Captain James McCleave was captured.
Near the end of that employment, he encountered the Joseph R. Walker exploratory party near Pinos Altos when Swilling led the capture of the famous Apache chief Mangas Coloradas.
News of his successes spread eastward when two gold samples from Swilling's claim sent to General James Henry Carleton were forwarded for presentation to President Abraham Lincoln.
In the midst of all this activity, Jack Swilling married a young Mexican woman of Spanish heritage named Trinidad Mejia Escalante (1847–1925).
Swilling Irrigating and Canal Company started the small farming community of Phoenix that has since grown into one of the United States' largest metropolitan areas.
[16] Once Phoenix was well-established and the so-called "original townsite" was located over three miles (5 km) to the west of his holdings, he lost interest and moved his growing family back to central Arizona.
Trinidad Swilling suggested that he go on a trip to recover and rebury the remains of their old friend, Colonel Jacob Snively, who had been killed by Apaches in the Wickenburg Mountains near the peak called White Picacho.
[20] After his death, Swilling's reputation as a badman grew so fast that by the end of the 19th century a prominent Arizona historian described him as a "typical desperado."
Friends remembered Jack Swilling as an honest, hard-working, and generous man always ready to help those in need of a meal or a place to sleep.
[21] On Thursday afternoon, February 19, 1931, the Maricopa Chapter of the Daughters of the American Revolution, in a simple ceremony with the presence of Arizona Governor George W. P. Hunt, unveiled and dedicated to the memory of Jack and Trinidad Swilling, a fountain which stands in the park directly in front of the courthouse building in Phoenix.
Jack W. Swilling, 1831–1878, who built the first modern irrigation ditch, and Trinidad, his wife, 1850–1925, who established in 1868 the first pioneer home in the Salt River Valley."