William Mosby Eastland was born in Kentucky to Thomas Butler and Nancy Mosby Eastland. The Eastland, Dawson and Moore families were related and it is believed that after John Henry Moore migrated to Texas he wrote to his family and friends describing the great opportunities and possibilities to be found in Texas. William Mosby Eastland was the first to follow Moore to Texas. In 1833 he settled in the area, built a saw mill, and engaged in the lumber business. His brother Nicholas Washington Eastland, his nephew Robert Moore Eastland and his cousin Nicholas Mosby Dawson along with other family members soon followed William to Texas. John Henry Moore, William Mosby Eastland and Nicholas Mosby Dawson, were destined to play courageous and spectacular roles in the history of Texas. Eastland began his military service in July 1835 when he was appointed first lieutenant of a volunteer company under Colonel John Henry Moore in a three month campaign against the Waco and Tawakoni Indians. On his return, he joined the volunteer army of Texas and participated in the “Storming and Capture of Bexar” in December 1835.