 Complete the following phrase:  McClellans plan initially was to utilize the James and York rivers, especially the former, which was known to be navigable to Richmond, in combination with his land-based forces, to attack simultaneously and overwhelm the unknown resources of the rebels at Richmond. However, even as several months were spent through the winter of 1862 training new troops and bringing these many Union assets into position, the portion of the scheme which depended upon control of the James River ran into trouble. In March, the 