Jack participated in the capture of Goliad, after which, although he expressed considerable misgivings about the wisdom of attacking Gen. Martín Perfecto de Cos, Stephen F. Austin appointed Jack "Brigade Inspector" of the Texas army with the rank of major and ordered him to Bexar. With James Bowie, Jack commanded the Texas troops at the Grass Fight on November 26, 1835. In this engagement, Jack wrote to Gen. Edward Burleson, "the first division flanked to the right and the second to the left and in a few moments the ditch and field were cleared of every Mexican except their dead & wounded." When Gen. Antonio López de Santa Anna marched into Texas, Jack sent his family to the Neches River for safety while he joined Sam Houston's army. At the battle of San Jacinto, Jack was a private in Capt. William Hester Patton's Fourth Company - the so-called Columbia Company - of Col. Sidney Sherman's Second Regiment, Texas Volunteers. He was discharged on May 30, 1836.
On April 2 Jack was appointed secretary of state in the administration of David G. Burnet. As a cabinet member he objected strongly to the release of Santa Anna, not wishing to see him "turned loose upon the world to seek for other opportunities to glut his cannibal thirst." His health being, he wrote to Burnet, "extremely bad," Jack tendered his resignation on August 9, 1836, but remained in the cabinet until October 22, 1836, when he was elected judge of the Brazoria district court. According to Henry Millard, Stephen F. Austin was going to appoint Jack chief justice of the Texas Supreme Court if Austin had been elected president of the republic in 1836. Jack served as compiler of the laws during the administration of Mirabeau B. Lamar but resigned at the end of 1838. He was elected to the House of Representatives of the Fourth Congress of the Republic of Texas from Brazoria County and served on the State of the Republic and the Judiciary committees, 1839-40. By 1840 he owned 2,574 acres in Brazoria County, plus seventeen town lots in Velasco and two more in Brazoria, thirty-one slaves, six horses, seventy-five cattle, two gold watches, and a silver watch. At the resignation of Timothy Pillsbury, Jack was elected to the Senate of the second term of the Sixth Congress; he was reelected to the Seventh and Eighth congresses and served until 1844.
In response to Rafael Vásquez's raid of 1842, Jack volunteered for service in Capt. John Porter Gill's company of Col. Clark L. Owen's regiment and served from March 20 until June 20, 1842. He drafted a series of resolutions favoring war with Mexico that were adopted at a public meeting in Galveston on April 24, 1842, but in July he voted against Sam Houston's war bill in the Senate because he thought the use of militia for offensive purposes to be unconstitutional. Politically, he was a member of the party of Mirabeau Lamar and was generally opposed to the policies of Sam Houston.
Jack died of yellow fever on August 20, 1844, at the Brazoria County plantation of Hiram George Runnels. His brother Patrick had died of the same illness only sixteen days earlier, on August 4, in Houston. William H. Jack was buried on his Brazoria County plantation. Later, however, his remains were removed to Galveston and reinterred in Lakeview Cemetery. He was the father of Thomas McKinney Jack and the father-in-law of William Pitt Ballinger and Guy Morrison Bryan. Jack County was named in honor of William Houston and Patrick C. Jack. Laura Jack died at Galveston on February 24, 1877. Source
30° 15.915, -097° 43.620
Texas State Cemetery