Original Cost: $111 billion
Inflation Adjusted Cost: $698 billion
Like the Korean War, the Vietnam War was another proxy war in the broader Cold War with North Vietnam supported by its communist allies and South Vietnam supported by the United States and its allies. Americans were deeply divided over the costs and benefits of the longest war in its history, including the deaths of over 58,000 US servicemen.
(Pictured: Pres. Lyndon Johnson and Sen. Richard Russell)