Arriving in Arizona Territory during the American Civil War, he settled in the Salt River Valley.

There he performed the survey work required to create the town of Phoenix as well as holding a variety of governmental offices at the city and county levels.

[1] In 1864, during the American Civil War, Hancock enlisted in Company K of the 7th Regiment California Volunteer Infantry.

[1] There, on November 10, 1870, he was hired by the Salt River Valley Town Association to survey and plat a townsite for the foundation of Phoenix.

[4] By December 10, Hancock had completed enough surveying work to allow for initial sale of plots on the eastern side of the new town.

[6] Hancock continued to perform survey and civil engineering work in the Salt River Valley for several years.

[1] In 1900, Hancock proposed a company that would build flood control dams and provide irrigation water to 275,000 acres (1,110 km2) of land in the Salt River valley.