Others, like cowardice, desertion, and insubordination, are purely military crimes. Crimes such as desertion and adultery were punishable by death. It was very difficult to secure divorce on the grounds of adultery, desertion, or cruelty. Of those 44, 4 were executed on charges of desertion, rather than mutiny. There is a difference between desertion and treason. Confederate policies regarding desertion generally were severe. There is disagreement whether the Union army used branding as a punishment for desertion. Irma Warner sued her husband for divorce on the grounds of desertion. The couple remained legally married until 1921, when Acker sued Valentino for divorce, citing desertion. They flee to friendly lines, but are accused by Lieutenant Ito of desertion. History has condemned his departure as a desertion. Greater sage-grouse apparently have high rates of nest desertion and nest predation. The Confederate army, in contrast, had difficulty replacing men lost through battle, disease, and desertion. Lee's army, thinned by desertion and casualties, was now much smaller than Grant's. The Marine Corps showed 1,603 Marines in desertion status in 2001.