Born in Massachusetts, Samuel C. Pomeroy was serving in Congress when President Franklin Pierce signed the Kansas-Nebraska Act of 1854 into law, Pomeroy is reported to have said to the President:
“Your victory is but an adjournment of the question from the halls of legislation at Washington to the prairies of the freedom-loving West, and there, sir, we shall beat you.”
Pomeroy signed on to be an agent of the New England Emigrant Aid Company in Kansas, arriving in September of 1854 and helping to found the town of Lawrence. Present in Lawrence in May of 1856, Pomeroy surrendered the town's armaments to the US Deputy Marshall as an attempt to prevent any violence from occurring. After the US Deputy Marshall left the scene, Douglas County Sheriff Samuel Jones enlisted the posse and carried out the Sack of Lawrence.
After spending some time in Lawrence, Pomeroy moved to Atchison, Kansas, to purchase the pro-slavery Squatter Sovereign newspaper, which he turned into a free-state newspaper. Pomeroy was elected mayor of Atchison, serving from 1858-1859. When Kansas was admitted to the Union in January 1861, Pomeroy was elected a one of the state’s U.S. Senators. After losing his bid for a third Senate term, Pomeroy returned to his native state of Massachusetts.
During the Battle of Westport, Pomeroy volunteered to serve as an aide to Maj. Gen. Samuel R. Curtis.