In the time in which Washington decided to vaccinate all of his troops to keep them healthy, there were several sicknesses going around and wiping out other troops. Between fighting the British and having the risk of smallpox infecting his troops, it was a small risk to take vaccinating them. It ended up helping a lot, as they only had to be worried about the British then. The smallpox would wipe out a lot of the American troops, so on Washington's behalf, it was super smart. Hope this helps and if you have any other questions feel free to ask!
