Yes, Spencer, but at the cost of many, many, many more lives. The Japanese refused to surrender. They believed their emperor was a god and their god told them it was shameful to surrender. They no longer had an air force, they no longer had a navy, and even after the first bomb, the refused to stop. Only the second bomb brought the emperor to his senses. Yes, the US and its allies could have marched into Tokyo without the bomb, but it would have taken longer, and many more lives would have been lost.