Is it fair to say that the Americans winning the Revolution was a combination of tactical advantage on their part and the fact that England just basically gave up?
It is fair to make this statement, but we should be aware that the strategic factors that contributed to the colonies’ victory were much more important than the tactical.
The American colonists did have some tactical advantages in the Revolutionary War. However, these tactical advantages were not all that great. The colonists lost many battles in this war. Had the war been simply a matter of military power, they would likely have lost. In some times and places, the Americans had tactical advantages. Perhaps the most important of these times and places was at Yorktown. There, the colonists and their French allies had a major tactical advantage conferred to them by the French sea victory that kept the British navy from evacuating the English army as it could otherwise have done. The colonists also had the tactical advantage of having roughly twice the manpower that the British did in that particular place. These tactical advantages allowed them to win the battle that ended the war.
However, it was the strategic advantages that were much more important. The colonies could surely not have beaten the British army militarily in the long term. The British won the majority of the pitched battles that were fought in this war. The colonies won a few, but often (as in the South) won the war by refusing to get into pitched battles and thus denying the enemy the ability to defeat them. This strategy only works if the enemy lacks the political will. The British did lack the political will. They were not fully committed to this war and they were not willing to do whatever it took to win it. Thus, the greater part of the American victory was the strategic part; it was the fact that the British essentially gave up.