On October 12, 1841, Terry married Mary Bingham, daughter of Francis Bingham, one of Stephen F. Austin's Old Three Hundred colonists in Texas. The couple had three sons and three daughters. On March 6, 1844, the Houston Telegraph reported that two insurgent slaves attacked Terry on his plantation with knives and axes, but "with admirable courage" he defended himself and managed to disable both men. Terry formed a partnership with William J. Kyle, and in 1851 they were awarded a contract to construct the first railroad in Texas, the Buffalo Bayou, Brazos and Colorado Railway, from Harrisburg, a small hamlet five miles from Houston, to the Brazos River and beyond to Richmond. Terry and Kyle used slave labor in the construction, which cost $18,400 per mile, but it was not until January 1856 that the tracks reached the Brazos some thirty miles from Harrisburg. Due to the railroad, however, a brisk trade began to move to Harrisburg. Houston was not to be outdone and received authorization from the state to finance a railroad and approval from its taxpayers to build the Houston Tap, as it was called, to connect with the Buffalo Bayou, Brazos and Colorado Railway at a point eight miles from Harrisburg. Terry and Kyle were also awarded the contract to build the Houston Tap. Terry had also purchased the Oakland sugar plantation in Fort Bend County in 1852 and became a prosperous sugar planter. In 1860 he and Kyle had real and personal property worth almost $300,000.
By reason of his wealth, large physical size, and popularity, Frank Terry became a leader in Fort Bend County, and on January 9, 1861, he was elected a delegate to the Secession Convention in Austin. Terry and two fellow delegates, Thomas S. Lubbock and John A. Wharton, conceived the idea of organizing at least one company of Texas cavalrymen for the new government. In February and March of 1861 Terry was one of the senior officers aiding John Salmon Ford and Ebenezar B. Nichols in the campaign to disarm the federal troops at Brazos Santiago. In June 1861 Terry, Lubbock, Wharton, and perhaps as many as fifty other Texans sailed from Galveston to New Orleans and then caught the train to Richmond to offer their services to the Confederate Army. In Richmond Terry and Lubbock secured positions as volunteer aides to Gen. James Longstreet. Both men were appointed colonel, a term attached as a courtesy for their volunteer service, and participated with distinction in the battle of First Manassas or Bull Run. Afterward, the Confederate War Department granted the authority to organize a cavalry regiment. At Houston on August 12, 1861, Terry and Lubbock issued a call for volunteers that was answered by 1,170 men.
The rangers were sworn into service in September, but Terry delayed their final organization until late November, when they were officially designated the Eighth Texas Cavalry. The regiment started immediately for Virginia but en route was diverted to Nashville and then later ordered to Bowling Green, Kentucky. Terry was killed in the first battle fought by the rangers near Woodsonville, Kentucky, on December 17, 1861. The battle, however, abruptly ended in a Confederate victory. Terry's body was sent by train to Nashville, Tennessee, where the legislature adjourned and joined in a procession escorting the remains to be held in state at the Tennessee Capitol. The body lay in state in New Orleans and then Houston, where the funeral procession was described as "the most imposing ever seen in this state." Governor Lubbock lauded Terry in the state Senate: "no braver man ever lived-no truer patriot ever died." Terry County was later named in his honor.
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