It seems that proclamations calling for days devoted to prayer and fasting or thanksgiving were pretty common in the Civil War era – both North and South. 150 years ago today President Lincoln issued the following:
PROCLAMATION RECOMMENDING THANKSGIVING FOR VICTORIES,
APRIL 10, 1862.
BY THE PRESIDENT OF THE UNITED STATES OF AMERICA:
It has pleased Almighty God to vouchsafe signal victories to the land and naval forces engaged in suppressing, an internal rebellion, and at the same time to avert from our country the dangers of foreign intervention and invasion.
It is therefore recommended to the people of the United States that at their next weekly assemblages in their accustomed places of public worship which shall occur after notice of this proclamation shall have been received, they especially acknowledge and render thanks to our Heavenly Father for these inestimable blessings, that they then and there implore spiritual consolation in behalf of all who have been brought into affliction by the casualties and calamities of sedition and civil war, and that they reverently invoke the divine guidance for our national counsels, to the end that they may speedily result in the restoration of peace, harmony, and unity throughout our borders and hasten the establishment of fraternal relations among all the countries of the earth.
In witness whereof I have hereunto set my hand and caused the seal of the United States to be affixed.
Done at the city of Washington, this tenth day of April, A.D. 1862, and of the independence of the United States the eighty-sixth.
By the President: WILLIAM H. SEWARD, Secretary of State.
You can read more of President Lincoln’s writings at Project Gutenberg