Most of the American soldiers had not been paid in months and many of the promised pensions never came.
The American revoluntionary war was fought by a lot of paid militias who were being paid a good salary.
Once the war was coming to a close, these soldiers were not paid on time and many of the injured and veterans never got the pension funds they were promised.
Eventually, this was creating unease among the soldiers. There were even talks of a coup d'etat against the United States Congress. The event is also known as the Newburgh Conspiracy.
George Washington personally stepped in to ensure that the young democracy was derailed. He gave an emotional speech on the importance of the congress and eventually reached a settlement where paid some of the unsettled salaries and instead of offering half-pay pensions, settled on paying full salary for 5 years.