At some points this became a positive embarrassment to Union commanders. A few days after General Butler took command of the Union troops at Fortress Monroe in May, 1861, the agent of a rebel master came to insist on the return of three slaves, demanding them under the fugitive-slave law. Butler replied that since their master claimed Virginia to be a foreign country and no longer a part of the United States, he could not at the same time claim that the fugitive slave law was in force, and that his slaves would not be given up unless he returned and took the oath of allegiance to the United States. In reporting this, a newspaper pointed out that as the breastworks and batteries which had risen so rapidly for Confederate defense were built by slave labor, negroes were undoubtedly "contraband of war," like powder and shot, and other military supplies, and should no more be given back to the rebels than so many cannon or guns. The idea was so pertinent, and the justice of it so plain that the name "contraband" sprang at once into use. But while this happy explanation had more convincing effect on popular thought than a volume of discussion, it did not solve the whole question. By the end of July General Butler had on his hands 900 "contrabands," men, women and children of all ages, and he wrote to inquire what was their real condition. Were they slaves or free? Could they be considered fugitive slaves when their masters had run away and left them? How should they be disposed of? It was a knotty problem, and upon its solution might depend the loyalty or secession of the border slave States of Maryland, West Virginia, Kentucky and Missouri, which, up to that time, had not decided whether to remain in the Union or to cast their fortunes with the South. In dealing with this perplexing subject. Mr. Lincoln kept in mind one of his favorite stories: the one on the Methodist Presiding Elder who was riding about his circuit during the spring freshets. A young and anxious companion asked how they should ever be able to cross the swollen waters of Fox River, which they were approaching, and the elder quieted him by saying that he made it the rule of his life never to cross Fox River until he came to it. The President, following this rule, did not immediately decide the question, but left it to be treated at the discretion of each commander. Under this theory some commanders admitted black people to their camps, while others refused to receive them. The curt formula of General Orders: "We are neither negro stealers nor negro catchers," was easily read to justify either course. Congress greatly advanced the problem, shortly after the battle of Bull Run, by passing a law which took away a master's right to his slave, when, with his consent, such slave was employed in service or labor hostile to the United States.