The Maryland Constitutional Convention, 1864
During the Civil War, President Abraham Lincoln's Emancipation Proclamation of 1863 freed slaves in Confederate states but not in the Union state of Maryland. Indeed, Maryland's Constitution of 1851 had forbidden passage of "any law abolishing the relation of master or slave, as it now exists in this State" (Art. 3, sec. 43). To end slavery, Maryland had to write a new constitution.
Governor Augustus W. Bradford, in his annual message of 1864 to the General Assembly, sought passage of a constitutional convention bill. The predominently Unionist legislature promptly complied, and the electorate approved the call for a convention (Acts of 1864, ch. 5).
Delegates to the Constitutional Convention of 1864 were elected by the voters on April 6, 1864. The convention convened in Annapolis on April 27, 1864, and adjourned on September 6, 1864. The third state constitution, which abolished slavery in Maryland, received approval of the voters on September 18, 1864, and took effect November 1, 1864. — MD Archives
That hereafter, in this State, there shall be neither slavery nor involuntary servitude, except in punishment of crime, whereof the party shall have been duly convicted: and all persons held to service or labor as slaves are hereby declared free.