Watson Carvosso Squire, attorney, Civil War veteran, industrialist, and elected official, was born May 18, 1838, in Cape Vincent, New York. He was the only son of Rev. Orra Squire, a Methodist Episcopal minister of English ancestry. His mother, Erretta Wheeler, was a descendant of pre-Revolutionary War English immigrants. Squire was educated in public schools, at Falley Seminary in Fulton, and at Fairfield Seminary in Herkimer County, New York. In 1859 he graduated from Wesleyan University in Connecticut. He read law in Herkimer, New York, and shortly afterward was made principal of the Moravia Institute of Moravia, New York.

When the Civil War broke out, Watson Squire enlisted in the New York State service for two years. He was elected 1st lieutenant and commissioned in Company F of the New York Volunteers 19th Infantry Regiment. Squire served on the upper Potomac at Harper's Ferry under General Banks and in Virginia. He was engaged in several skirmishes and expeditions. Squire was honorably discharged, and in October 1861 he returned north to Ohio. He read law and graduated from Cleveland Law School in June 1862. When the call came for more men, Squire raised the 7th Independent Company of Ohio Sharpshooters, and on November 11, 1862 he was commissioned as Captain. His company fought on the Tennessee River and later escorted General Sherman on his march to the sea. During these campaigns, Squire served as judge advocate of the general courts martial. Later he was made judge advocate of the district of Tennessee. He served on the staff of Major General Rousseau as judge advocate and also under Major General Thomas during the siege and battle of Nashville. He also participated in the battles of Chickamauga, Resaca and Missionary Ridge. He was promoted to the rank of brevet colonel. Squire was mustered out of the army July 28, 1865.

After the war, Squire joined the E. Remington & Sons, the arms manufacturer based in Ilion, New York. He married Ida Remington, the daughter of company president Philo Remington in 1868 and became in turn manager, treasurer, and secretary of the company. Squire promoted and sold primarily Remington arms, but he also marketed the company's sewing machines and typewriters. In the years following the Civil War, the development of the breech-loading rifle led to a great demand for Remington's product. Much of Remington's business was abroad, and Squire dealt with the representatives of France, Russia, Spain, Denmark, Sweden, Egypt, Mexico, and other countries. During the Franco-Prussian War of 1870-71, Remington handled purchases for France. From 1877 to 1879, he traveled extensively in Europe and Mexico. He spent several months of 1877 in St. Petersburg, and in 1878 visited Madrid, Paris, Turin, and Stockholm.

Squire moved to Seattle in 1879 to attend to the development of lands which he had purchased from Philo Remington. He constructed buildings and houses in Seattle, and cleared farmland in the White River Valley. Squire's ownership of the Seattle properties was later contested in an unsuccessful lawsuit ( Shepard, et al., v. Squire ) brought by Remington's former partners. At the time of the lawsuit (ca. 1894), the property was worth about $1,000,000. After moving West, Squire divided his time between Seattle and New York. He maintained his ties with the Republican Party in New York State. In 1872, Squire was a member of the Republican executive and finance committees and became acquainted with Presidents Garfield and Arthur. Squire sold his interest in the Remington Arms Company in 1884 and in the same year was appointed Governor of Washington Territory by President Arthur. He served in this position until 1887. As governor, Squire was faced with the task of maintaining law and order during the anti-Chinese riots in Tacoma and Seattle. These troubles began in 1885 and peaked on February 8, 1886, when Squire declared martial law and inaugurated a military system of government until order was restored. Martial law was withdrawn on February 22. At the request of the State Department, Governor Squire afterwards investigated the losses of property by the Chinese.

Squire was replaced as governor in 1887 by Eugene Semple, a Democratic appointee. In January 1889, Squire was made president of the Statehood Convention in Ellensburg, which met to urge admission of Washington as a state. Later that year, he was elected to the U.S. Senate by the state legislature. He was re-elected in 1891. In the Senate, Squire won appropriations for improvements of the rivers and harbors of the state and secured a naval station (later the Puget Sound Naval Shipyards) at Bremerton. His most successful efforts were on behalf of coast defenses.

After his defeat in the election of 1897, Squire practiced law and managed his properties. He founded and was president of Union Trust Co. (later the Squire Investment Co.), which was established to administer his properties. Watson Squire died in Seattle on June 7, 1926.