At some points, indeed, this tendency created an embarrassment to Union commanders. A few days after General Butler assumed command of the Union troops at Fortress Monroe, the agent of a rebel master who had fled from the neighborhood came to demand, under the provisions of the fugitive-slave law, three field hands alleged to be in Butler's camp. Butler responded that as Virginia claimed to be a foreign country the fugitive-slave law was clearly inoperative, unless the owner would come and take an oath of allegiance to the United States. In connection with this incident, the newspaper report stated that as the breastworks and batteries which had been so rapidly erected for Confederate defense in every direction on the Virginia peninsula were built by enforced negro labor under rigorous military impressment, negroes were manifestly contraband of war under international law. The dictum was so pertinent, and the equity so plain, that, though it was not officially formulated by the general until two months later, it sprang at once into popular acceptance and application; and from that time forward the words "slave" and "negro" were everywhere within the Union lines replaced by the familiar, significant term "contraband." While Butler's happy designation had a more convincing influence on public thought than a volume of discussion, it did not immediately solve the whole question. Within a few days he reported that he had slave property to the value of $60,000 in his hands, and by the end of July nine hundred "contrabands," men, women, and children, of all ages. What was their legal status, and how should they be disposed of? It was a knotty problem, for upon its solution might depend the sensitive public opinion and balancing, undecided loyalty and political action of the border slave States of Maryland, West Virginia, Kentucky, and Missouri. In solving the problem, President Lincoln kept in mind the philosophic maxim of one of his favorite stories, that when the Western Methodist presiding elder, riding about the circuit during the spring freshets, was importuned by his young companion how they should ever be able to get across the swollen waters of Fox River, which they were approaching, the elder quieted him by saying he had made it the rule of his life never to cross Fox River till he came to it.