British and French empires. The ports of the British West Indies were closed to all staple products which were not carried in British ships. France and Spain established similar policies. Simultaneously, new manufacturers faced sharp competition from British products which were suddenly available again. Political unrest in several states and efforts by debtors to use popular government to erase their debts increased the anxiety of the political and economic elites which had led the Revolution. The apparent inability of the Congress to redeem the public obligations (debts) incurred during the war, or to become a forum for productive cooperation among the states to encourage commerce and economic development, only aggravated a gloomy situation. In 1786–87, Shays' Rebellion, an uprising of dissidents in western Massachusetts against the state court system, threatened the stability of state government. The Continental Congress printed paper money which was so depreciated that it ceased to pass as currency, spawning the expression "not worth a continental". Congress could not levy taxes and could only make requisitions upon the States. Less than a million and a half dollars came into the treasury between 1781 and 1784, although the governors had been asked for two million in 1783 alone. When John Adams went to London in 1785 as the first representative of the United States, he found it impossible to secure a treaty for unrestricted commerce. Demands were made for favors and there was no assurance that individual states would agree to a treaty. Adams stated it was necessary for the States to confer the power of passing navigation laws to Congress, or that the States themselves pass retaliatory acts against Great Britain. Congress had already requested and failed to get power over navigation laws. Meanwhile, each State acted individually against Great Britain to little effect. When other New England states closed their ports to British shipping, Connecticut hastened to profit by opening its ports. By 1787 Congress was unable to protect manufacturing and shipping. State legislatures were unable or unwilling to resist attacks upon private contracts and public credit. Land speculators expected no rise in values when the government could not defend its borders nor protect its frontier population. The idea of a convention to revise the Articles of Confederation grew in favor. Alexander Hamilton realized while serving as Washington's top aide that a strong central government was necessary to avoid foreign intervention and allay the frustrations due