Just in time for the anniversary of the battle of Chancellorsville, there is a new theory as to why Lt. Gen. Thomas “Stonewall” Jackson’s own men fired on him, mortally wounding him on the evening of May 2, 1863.

This is an undated portrait drawing of Thomas Jonathan "Stonewall" Jackson, the Confederate general during the American Civil War, 1861-65. Stonewall Jackson died from wounds received at Chancellorsville in May, 1863. (AP Photo/ASSOCIATED PRESS)

The incident has fascinated historians and Civil War students for the 150 years since it happened following one of Jackson’s most daring but successful military maneuvers, his flank attack.

Astronomers Don Olson and Laurie E. Jasinski posit that the moon that night lit him from the back, obscuring his identity by making him visible only as a silhouette, according to an article in the online, subscription magazine Sky and Telescope that is cited in World Science, a publication of Texas Stare University. Jackson and some of his officers had ridden out beyond their own lines, and, when returning, were fired on by men of the 18th North Carolina Infantry who did not recognize them.

The accidental shooting is usually attributed to the general prohibition about getting out front of your own lines without the widespread knowledge of others, low visibility and the trees and heavy undergrowth that also obscured Jackson and his men.