Yeah, Washington was a great military leader. He lead 12 major battles in the Revolutionary War and went 7-5, which was pretty good considering the "Redcoats" had a much superior army and navy at the time. However, people don't know Washington's military history. He actually had one of the worst military blunders in history. When he attacked Fort Necessity, he triggered off the Seven Years' War - French and Indian War. Considering the Continental Army had only 19,000 regulars and the rest was militia Washington did well. However, as much as I love Washington, the article is inaccurate, for sure. Washington never showed he was a tactician and was a political appointment in any case. However, he did show he was resilient and dedicated his life to the cause.
Nonetheless, to say he was Britain's greatest enemy commander is a fallacy. The British could have easily won the Revolutionary war. First, the British parliament was split on its views of America, some supported the rebels, some opposed them, hence, this brought discord in parliament, which they never had any real strategy to win the war. Second, the British were more focused on the French (their imperial rival), the French backed America just to spite the British, because they lost their main colony to them (Canada). Consequently, the French added more muscle to America, and also used diversionary tactics by attacking Gibraltar, therefore, the Royal Navy was dispatched to the Mediterranean, which lead to General Cornwallis' defeat at Yorktown, this was the turning point of the war, and lead the British parliament to vote to end the war. The Mediterranean was more important to the Brits than America was in commercial terms.
The Revolutionary war was far from a defeat for Britian. The war bankrupted the French, which lead to Britain being the sole imperial power in the world. The Brits and America re-established trade, the Brits kept the West Indies, which was more economically valuable than America. Moreover, the Brits colonized India (the crown jewel). Some historians say, the Brits wanted to lose America as its colony because Americans were too demanding, and the British people's taxes were basically keeping America a float. The average British citizen was paying more taxes to fund America than the average American was, also, the colonists were all basically British, therefore, the Brits and the Americans were brethren, which made the Brits reluctant to go to war with America.
Washington was a great leader, and I believe was the greatest American ever, his presidency speaks volumes, but to say he caused the British demise is a joke. The British Empire actually got bigger after its loss to America...
References:
Philippa Levine, The British Empire: Sunrise To Sunset.
Ellis Wasson, Modern Britain: 1714 to the present.