Origin of the blank check: How the Vietnam war started from a battle that never happened
On the record, the U.S. never officially declared war on Vietnam, as such a measure was never passed through congress. Lyndon B. Johnson, the U.S. president at the time however, did get a blank check from Congress for "any measures" against the North Vietnam state as a reprisal for an attack that never happened in the Gulf of Tonkin.
