Sadler was married in March 1837 in Nacogdoches County to Mary Murchison, a daughter of Martin Murchison who had been born in South Carolina and later spent some years in Alabama. Martin Murchison brought his wife, oldest son John and daughter Mary to Texas in 1835. John Murchison, born about 1807, had then enlisted in the volunteer army from April 24 to July 24, 1836, before settling back to farming in East Texas. The Murchison family lived several miles south of Sadler's home in an area of present northern Houston County that had become known as Murchison's Prairie.
William and Mary Sadler's new home was located just north of the current county line of Anderson County. Although he owned one-third of a league of land near Fort Houston, Sadler chose to establish his permanent homestead closer to the Neches River. Now married, he was able to take possession of a full league and labor of land from Texas for meeting the requirements of an early settler. It was on this large piece of land that he settled, although he would not receive clear title to it until early in 1838 after present Houston County was firmly established. Settlers moving into Texas prior to March 2, 1836, were generally issued First Class Headrights for a league of land. The couple's home was located across a cornfield from a cluster of trees that stands beside present FM 2022 near the community of Percilla, Texas.
Should the Indians of the area become a threat again, Sadler and his Fort Houston area volunteers could expect little help from the Texas Army. Since its peak enlistment in July 1836, the army's numbers had steadily decreased. Albert Sidney Johnston was appointed commander of the Texas Army with the rank of brigadier general, but his second-in-command, General Felix Huston, challenged him to a duel for the post. Johnston was seriously wounded and had to depart Texas for some time to recover. In his absence, command of the army went to Colonel Samuel Rogers on May 7. On May 18, President Houston furloughed all the two-thousand- man army except for about six-hundred men. This number dwindled as men began quitting the service and once again the benefit of the few Texas Rangers companies in existence became apparent.
The lack of proper protection on the early Texas frontiers left the doors open for the more hostile Indians to pillage the generally helpless settlers. Another assault occurred just a few miles from Sadler's new home on May 10, 1837. Two of the area's earliest residents, Dan McLean and his brother-in-law John Sheridan, were considered expert Indian fighters and were employed at times by the area's settlers as guides and protectors. While assisting the locals to recover stolen horses, both men were ambushed and killed by Indians. Near the present community of Slocum on FM 2022 now stands a Texas State historical marker which identifies the site of the McLean-Sheridan Massacre near Sadler's home. Sheridan's wife Lucinda traveled to the scene of the massacre with an oxcart shortly thereafter and brought back the bodies to be buried on their respective properties several miles south.