George Washington could be considered America's greatest general by many. Washington's brilliant leadership was able to transform a rag-tag militia into a fighting force which defeated the world's greatest army at the time: the British Empire. Furthermore, Washington had the foresight to inoculate his troops against smallpox, a deadly disease at the time, which claimed many soldiers.
There have been other good generals in the United States, but George Washington is the greatest. Not only did he inoculate his troops, he won against overwhelming odds against the British. He had a brilliant ground game, and that is how he was able to defeat larger armies. He also inspired his troops more than anyone.
George Washington is this country's greatest general. He rallied the underdog troops, which were at a severe resource disadvantage to the British, for the long war. He also voluntarily gave up his power, showing the separate powers for the military and the government. He is the standard in which all future generals were to be held.
There have been generals since then that might have actually scored bigger victories on the battlefield and possibly even have been better strategists. However, with Washington, our country would not even exist, so an argument can be made he is our best ever. Some other generals might deserve consideration, but it is subjective in the end.