The Spanish-American War is most often remembered for Teddy Roosevelt and the beginnings of the modern American army. Causes of the conflict reached back years earlier, as America was wary of continual Spanish involvement in its part of the hemisphere.  The sinking of the USS Maine in a Havana harbor proved to be the last straw. Signed into law by President William McKinley, the War Revenue Act of 1898 provided for the taxation of liquor, tea, tobacco, among other goods and services, and introduced the first estate tax. The act also authorized the Treasury Department to sell some $200 million in three percent bonds, creating a surplus in revenue for the nation's treasury. Fewer than twenty bonds from this series are known today.