The house of Mary Thompson, also known as Lee’s Headquarters, is on the north side of Chambersburg Road on Seminary Ridge on the west side of Gettysburg.
The house was an excellent candidate for Robert E. Lee’s headquarters. It was next to the main road coming into Gettysburg from the west, on which the rest of Lee’s army would arrive after July 1. The house was at the top of a ridge with an excellent view in all directions. And it was at the centre of the Confederate lines. Although Lee spent much of his time in the saddle at Gettysburg, he is known to have taken a meal and slept in the house on July 1. Even when Lee was not personally present, the house was the communications centre where messengers brought news of the battle to Lee’s staff and took away orders.