His father was in business and moved to Haverhill, Massachusetts, where he began manufacturing boots and shoes until 1839.

Farnham entered the junior class University of Vermont, where he was a member of the Lambda Iota Society:[1] graduated in 1849, and earned a degree of A. M. in 1852.

During the early part of the Civil War, Farnham was a second lieutenant in the Bradford Guards, a company in the 1st Vermont Infantry.

Later, he was a captain and then the lieutenant colonel of the 12th Vermont Infantry, and for nearly half the term of his nine months of service was in command of the regiment.

[2] After the war, Farnham resumed practice of law at Bradford, and was Republican candidate for representative in the Legislature, but was defeated.