They ran from the northeast side of Richmond to the James River, then jumped over the James to its southern side, where they slowly extended out to the south and southwest of Petersburg. Roughly thirty-seven miles of offensive and defensive lines were established, and no one can calculate how many metric tons of earth were moved. Throughout these long lines were ditches and trenches, but also temporary housing, which ranged from tents to makeshift shelters to the occasional house. The civilians had, naturally, fled, and the few houses that remained were commandeered. As time passed, the Northern men put up towers, not to use in the style of medieval siege towers, but to observe what happened in the enemy lines.