In 1834, Lee was transferred to Washington as General Gratiot's assistant. Lee had hoped to rent a house in Washington for his family, but was not able to find one; the family lived at Arlington, though Lieutenant Lee rented a room at a Washington boarding house for when the roads were impassable.  not found] In mid-1835, Lee was assigned to assist Andrew Talcott in surveying the southern border of Michigan.  While on that expedition, he responded to a letter from an ill Mary Lee, which had requested he come to Arlington, "But why do you urge my immediate return, & tempt one in the strongest manner[?] . . . I rather require to be strengthened & encouraged to the full performance of what I am called on to execute. " Lee completed the assignment and returned to his post in Washington, finding his wife ill at Ravensworth. Mary Lee, who had recently given birth to their second child, remained bedridden for several months. In October 1836, Lee was promoted to first lieutenant.