I'm reading a fascinating biography of Robert Morris, the Philadelphia merchant who managed the revolutionary government's finances and arranged for clandestine acquisition of supplies for Washington's army.
In September, 1776, he and Ben Franklin were the only active members
of the Committee on Secret Correspondence when they learned of French
willingness to provide support to the rebels.
Franklin and Morris informed only the presiding officer of the Continental Congress on October 1, in a letter of explanation:
"We agree in opinion that it is our indispensable duty to keep it a secret, even from Congress..."
"We find, by fatal experience, the Congress consists of too many members to keep secrets...."