On May 30, 1861, Secretary of War Simon Cameron wrote General Benjamin Butler at Fortress Monroe to inform him officially of the cabinet’s approval of his decision not to return the slaves of disloyal Virginia slaveholders and declare them contraband of war. Cameron’s letter read:
Sir: Your action in respect to the negroes who came within your lines from the service of the rebels is approved. The Department is sensible of the embarrassments which must surround Officers conducting Military operations in a State by the laws of which Slavery is sanctioned. The Government cannot recognize the rejection by any State of its Federal obligations, nor can it refuse the performance of the Federal obligations resting upon itself. Among those Federal obligations, however, no one can be more important than that of suppressing and dispersing armed combinations, formed for the purpose of overthrowing its whole constitutional authority.
While, therefore, you will permit no interference, by the persons under your command, with the relation of persons held to service under the laws of any State within which your Military operations are conducted, and under control of such armed combinations, refrain from surrendering to alleged masters any persons who may come within your lines. You will employ such persons in the services to which they may be best adapted, keeping an account of the labor by them performed, of the value of it, and of the expenses of their maintenance. The question of their final disposition will be reserved for further determination.
In short, Lincoln’s cabinet essentially approved everything Butler had done in regard to fugitive slaves in Virginia making “contraband of war” an official policy. From the perspective of the Lincoln administration, Benjamin Butler’s extemporaneous decision well served its needs as they existed in late Spring 1861. It encouraged the loss a valuable military asset–slave labor–to the Confederacy, while not challenging slavery’s legality itself. The latter point was critical because at that moment Lincoln did not to do anything that would alienate slaveholders in the remaining loyal slave states. (Which explains why Lincoln and his cabinet would react very differently several months later when John C. Fremont actually tried to free the slaves of disloyal owners in Missouri.)
The key issue still remaining, of course, is summed up well by Simon Cameron in the final sentence of his letter to Ben Butler. He wrote, “The question of their final disposition will be reserved for further determination”–meaning Lincoln’s cabinet placed the exact status of the escaped slaves for the time being in a legal limbo. Brooks Simpson over at Crossroads is absolutely correct when he wrote that contraband of war policy for the slaves “effectively transferr[ed] their ownership to the United States of America (which is not the same thing as granting them freedom).” But if there was good news for the slaves, it was that federal government clearly was not interested in gaining permanent title to their ownership. Escaped slaves momentarily were useful to the Lincoln administration as temporary labor and in denying that same labor to the enemy. They also became useful bargaining chips. In the Preliminary Emancipation Proclamation in September 1862, Abraham Lincoln essentially would dangle their return to rebel slaveholders as a reward for resuming their loyalty to the United States. In the end, of course, that gambit would not succeed and the only workable solution was to free the contraband slaves and let them care for themselves, which was what the slaves who fled to Union lines wanted all along. Yet for the slaves at Fortress Monroe in late May 1861 it was enough for the moment they had escaped their owners and were now being paid for their work instead having it and their person and dignity stolen. Which would explain why many thousands of other slaves would follow the path they blazed in the weeks, months, and years that followed.
Source: Source: Private and Official Correspondence of Gen. Benjamin F. Butler During the Period of the Civil War, Vol 1. (Norwood, Mass.: The Plimpton Press, 1917), 119.