From the Texas Historical Marker for him, located along US 82 in Cooke County:
Born in Massachusetts. Moved to Texas 1836. Accepted post of Surveyor, Fannin Land District, helping settlers locate claims and fight Indians. Joined Snively Expedition to capture Mexican traders trespassing in Republic of Texas, 1843. Captain of Company in Mexican War, 1846. When Cooke County was created, 1848, Montague was named County Surveyor. Like most surveyors, took land as pay for duty that called for constant risk of life. Rifles to stand off Indians were in field kits. Like Surveyor-Senator John H. Reagan, Montague was honored in having a county named for him.
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This barely scratches the surface, but it is a good overview. Montague was incited to move here by the events of the Alamo and Goliad, although he arrived after the Battle of San Jacinto had been won. As mentioned, he was involved in surveying and "Indian fighting": one account indicates that his mop of red hair was prized by those who sought his scalp. Montague was a skilled merchant, and eventually saw service in the Mexican War.
Montague was a jury foreman in the Great Hanging at Gainesville, had a political career, and ultimately was so distraught over the South's loss in the Civil War that he left the country for Mexico. He did eventually return here, late in life, before dying in Marysville, TX.