The National Labor Union represented the first attempt to organize a national federation of labor in the United States. The germ of the idea for such a national federation of labor had been planted at the beginning of the Civil War, but it was not until 1866 that plans were set in motion to organize such a body. In February of that year William Harding, the president of the Coachmakers' International Union, met with Willam H. Sylvis, president of the Iron Moulders' International Union. A preliminary meeting called by these two leaders led to the convening of a national labor convention in Baltimore on August 20, 1866. From this modest beginning the National Labor Union quickly rose to a prominent position. The Chicago Tribune in 1869 estimated its membership at 800,000, and Sylvis himself put the figure at 600,000. Both estimates are undoubtedly exaggerated, but it is quite apparent that the organization represented a large proportion of the nation's laboring force and perhaps at its peak strength numbered between 200,000 and 400,000. The decline of the union was almost as spectacular as its rise, and by 1872 it was totally defunct.