Near the end of the war, Congress charged Deane with financial impropriety, and the British intercepted and published some letters in which he had implied that the American cause was hopeless.

[4] In 1761, Deane was admitted to the bar and practiced law for a short time outside of Hartford before moving to Wethersfield, Connecticut, and establishing a thriving business as a merchant.

[7] Deane excelled in the committee work of Congress, helping to coordinate the attack on Fort Ticonderoga and to establish the United States Navy.

[3] A dispute arose between Deane and fellow Connecticut delegate Roger Sherman over the appointment of Israel Putnam as a major general under George Washington's command.

[3][8] On March 2, 1776, Congress appointed Deane as a secret envoy to France with the mission of inducing the French government to grant financial aid to the colonies.

Deane organized the shipment of arms and munitions to the colonies with the assistance of Pierre Beaumarchais, the playwright and outspoken supporter of American independence.

[10][11] Deane also tacitly approved the plot of Scotsman James Aitken (John the Painter) to destroy Royal Navy stores and dockyards in Portsmouth and Plymouth, England, on behalf of the Continental cause.

[12] Deane's position was officially recognized after Benjamin Franklin and Arthur Lee arrived in Paris in December 1776, with orders from Congress appointing the trio as the diplomatic delegation to France.

[14] Deane arrived in Philadelphia on July 14, 1778, and was shocked when Congress accused him of financial impropriety on the basis of reports by his fellow commissioner Arthur Lee.

[3] Because Deane had left his account books in Paris, he was neither able to properly defend himself nor seek reimbursement for money he had spent procuring supplies in France.

[24] In March 1781, King George III approved a request from Lord North to bribe Deane in an attempt to recruit him as a spy and to influence Congress.

[25] However, in mid-July they cancelled their plan after the king read intercepted letters in which Deane described the military situation of the Colonies as hopeless and suggested a rapprochement with Britain.

He toured several manufacturing towns in England in late 1783, considering plans for steam engines that could operate grist mills, even consulting James Watt for advice.