Well this would give the ACLU fits today! On November 15, 1862 Lincoln sent out the following general order:
GENERAL ORDER RESPECTING THE OBSERVANCE OF THE SABBATH DAY
IN THE ARMY AND NAVY.
EXECUTIVE MANSION, WASHINGTON, November 15, 1862.
The President, Commander-in-Chief of the Army and Navy, desires and enjoins the orderly observance of the Sabbath by the officers and men in the military and naval service. The importance for man and beast of the prescribed weekly rest, the sacred rights of Christian soldiers and sailors, a becoming deference to the best sentiment of a Christian people, and a due regard for the divine will demand that Sunday labor in the army and navy be reduced to the measure of strict necessity.
The discipline and character of the national forces should not suffer nor the cause they defend be imperilled by the profanation of the day or name of the Most High. “At this time of public distress,” adopting the words of Washington in 1776, “men may find enough to do in the service of God and their country without abandoning themselves to vice and immorality.” The first general order issued by the Father of his Country after the Declaration of Independence indicates the spirit in which our institutions were founded and should ever be defended:
“The General hopes and trusts that every officer and man will endeavor to live and act as becomes a Christian soldier defending the dearest rights and liberties of his country.”
Sometimes there is an effort to portray Abraham Lincoln as some sort of unbeliever. That is completely mistaken. Lincoln struggled throughout his life to understand God, and in the agonies of War he achieved a profound faith in the Almighty. Like Saint Augustine, Lincoln could say, “Late have I loved thee!”