At the beginning of the war, when Boston was occupied by the British army and most supporters of independence were evacuated, Revere and his family lived across the river in Watertown. In 1775, Revere was sent by the Massachusetts Provincial Congress to Philadelphia to study the working of the only powder mill in the colonies. Upon his arrival in Philadelphia he met with Robert Morris and John Dickinson who provided him with the following letter to present to Oswald Eve:
bSir Philada. Novr. 21st 1775 I am requested by some Honorable Members of the Congress to recommend the bearer hereof Mr. Paul Revere to you. He is just arrived from New England where it is discovered they can manufacture a good deal of Salt Petre in Consequence of which they desire to Erect a Powder Mill & Mr. Revere has been pitched upon to gain instruction & Knowledge in this branch. A Powder Mill in New England cannot in the least degree affect your Manufacture nor be of any disadvantage to you. Therefore these Gentn & myself hope You will Chearfully & from Public Spirited Motives give Mr. Revere such information as will inable him to Conduct the bussiness on his return home. I shall be glad of any opportunity to approve myself. Sir Your very Obed Servt. Robt Morris P.S. Mr. Revere will desire to see the Construction of your Mill & I hope you will gratify him in that point. Sir, I heartily join with Mr. Morris in his Request; and am with great Respect, Your very hble Servt. John Dickinson
Mr. Eve complied with the letter completely and allowed Revere to pass through the building to obtain sufficient information, which enabled him to set up a powder mill at Canton.