60% of the soldiers were single, and their average age was 28. In many families, the younger sons joined the army while the fathers escorted the women and younger children east, away from the advancing Mexican army. 67% of the Texians who volunteered were from the Brazos Department, an impressive number considering the heavy losses many of these areas had sustained in the March fighting. 25% were from the Nacogdoches district, fewer than had served in 1835. Only 5% of the Texians were from the Bexar District. This number was low both because many of the volunteers had perished at the Alamo or Coleto and because the area was now occupied by the Mexican army. It was not only difficult for men to leave the area, but it was unwise to leave their families. The majority of the men from Bexar who served in April were cavalry officers under the command of Colonel Juan Seguin. An additional 623 men served in April outside of Houston's army. Less is known about these men, who had no central command or location. It is estimated that 31% were recent arrivals from the United States. They were older, with an average age of 34, and over 41% of them came from the Nacogdoches district. Historian Paul Lack described these men as a home guard, a "last line of defense" for the Texians. 398 men served in both 1835 and April 1836. Of these, 58% were single, with an average age of 30, and 26% had arrived in Texas after the war began. Of the Texians, 63% were from the Brazos district, 11% from Bexar, and 26% from Nacogdoches. Lack posits that many of those who chose not to re-enlist in April 1836 believed that they had done their duty. For the most part, they were older and, as they had been in Texas longer, they had more to protect. Believing the hostilities were over, by the end of May, most of the Texas residents had left the army, which shrank to 400 men. With fears of a Mexican counterattack spreading, more volunteers arrived from the United States. By June, the ranks had increased to 1300–1700 men, and by September to 2,500 men, spread across 53 companies. Of those in the army in September, 1,800 had come to Texas after the Battle of San Jacinto. Formation and structure The structure of the Texian Army was