In the United Staes, until recently, the inheritance tax has been employed principally as a war measure. The first one imposed was the stamp act of July 6, 1797, which was repealed five years later. The war revenue act of July 1, 1862, was repealed July 14 1870. The revenue act of August 27, 1894 was declared unconstitutional because of its income tax feature. The war revenue act of June 13, 1989 was repealed April 13, 1902. The present federal estate tax was formed September 8, 1916. It was later amended March 3, 1917, and was altered appreciably in the revenue act of October 3, 1917. The amendment increased the rates of the tax. The revenue acts of 1918, 1921, and 1924 changed the rates in varying ways and also changed many of the fundamental provisions. The revenue act of 1926, however, contains a retroactive provision which has the effect of nullifying the rates of the 1924 act and makes the rates of the 1921 act applicable until the effective date of the act of 1926 after which lower rates apply.