During the Civil War the key policy-maker in Congress was Thaddeus Stevens, as chairman of the Committee and Republican floor leader. He took charge of major legislation that funded the war effort and permanently transformed the nation's economic policies regarding tariffs, bonds, income and excise taxes, national banks, suppression of money issued by state banks, greenback currency, and western railroad land grants. Stevens was one of the major policymakers regarding Reconstruction, and obtained a House vote of impeachment against President Andrew Johnson (who was acquitted by the Senate in 1868). Hans L. Trefousse, his leading biographer, concludes that Stevens "was one of the most influential representatives ever to serve in Congress. dominated the House with his wit, knowledge of parliamentary law, and sheer willpower, even though he was often unable to prevail." Historiographical views of Stevens have dramatically shifted over the years, from the early 20th-century view of Stevens and the Radical Republicans as tools of enormous business and motivated by hatred of the white South, to the perspective of the neoabolitionists of the 1950s and afterwards, who applauded their efforts to give equal rights to the freed slaves.