On May 13th Joseph E. Johnston, the new overall commander for the Confederates in Mississippi, had ordered that Jackson be abandoned as Grant's troops were advancing. But the evacuation took time, and 150 years ago the 6,000 infantry under John Gregg were still guarding the town. Two Union corps advanced toward him, but they were held up by rainy weather. By 11 am serious fighting began and the Federals brought their superior numbers to bear, and Gregg's troops fell back slowly. Finally in the afternoon Johnston sent word that the evacuation was complete, and Gregg disengaged and fell back. In the day's fighting Gregg had lost about 850 men, the Federals – 286.