 The Powder-Mill on Frankford Creek became the working model that was studied by all the other colonies for building their own mills in the production of gunpowder.When the British occupied Philadelphia in September 1777, they took over the mill, and it was rumored that Eve cooperated.On March 6, 1778, the Supreme Executive Council found Eve found guilty of treason for trading with the British, but he was allowed to leave the city when the British evacuated in Spring 1778, leaving his son Oswell Jr. in charge of the mill.