As a matter of fact, the immense difficulty of capturing a city such as Vicksburg had not been realized until the work was actually undertaken. It was practically a fortress commanding the Mississippi, and whoever held it ruled the river. The Confederate leaders understood this very thoroughly and they had accordingly fortified the place, which was admirably adapted for defense, with great care and skill. In front of it flowed the Mississippi, twisting and turning in such snake-like conditions that it could be navigated only by boats of a certain length and build, and on either side of the city stretched wide swamp lands and bayous completely commanded by batteries well posted on the high ground occupied by the town. All this was formidable enough in itself, but shortly after Grant began his campaign, the river overflowed its banks and the whole country for miles was under water which, while not deep enough for steamers, was an absolute barrier to the approach of an army. Indeed, the capture of the city seemed hopeless from a military standpoint, but Grant would not abandon the task. Finding traces of an abandoned canal, he attempted to complete it in the hope of changing the course of the river, or at least of diverting some of the water from the overflowed land, but the effort was a stupendous failure almost from the start. Then he ordered the levees of the Mississippi protecting two great lakes to be cut, with the idea of flooding the adjacent streams and providing a waterway for his ships. This gigantic enterprise was actually put into operation, the dams were removed, and gun-boats were forced on the swollen watercourses far into the interior until some of them became hopelessly tangled in the submerged forests and their crews, attacked by the Confederate sharpshooters, were glad to make their escape. Week after week and month after month this exhausting work continued, but, at the end of it all, Vicksburg was no nearer capture than before. Indeed, the only result of the campaign was the loss of thousands of men who died of malaria, yellow fever, smallpox, and all the diseases which swamp lands breed. For this, of course, Grant was severely criticized and the denunciations at last became so bitter that an order removing him from the command was entrusted to an official who was directed to deliver it, if, on investigation, the facts seemed to warrant it.