Although the Union army had done precisely what Lee had hoped it would do, Lee's plan came to naught. The morning of the river crossing, Lee suddenly suffered a debilitating attack of diarrhea and was forced to remain in his tent, bedridden. Unfortunately, he had not sufficiently empowered a subordinate commander to take over during his illness. Lee lamented in his tent, "We must strike them a blow—we must never let them pass again—we must strike them a blow." But Lee lacked the means to execute his plan. Grant identified the situation he faced with a divided army and ordered his men to stop advancing and to build earthworks of their own.