[1] During the Civil War his father served as assistant surgeon while he enlisted into Company D, 135th Indiana Infantry at the age of 17.

[2] In 1884, Johnson was the Prohibition Party's candidate for Illinois Attorney General.

[3] In 1892, he was elected as the Prohibition Party's national chairman and served in that position until 1896.

[4] During the 1900 presidential election he ran for the Prohibition Party's presidential nomination, but withdrew shortly before balloting and supported John G. Woolley who was able to narrowly defeat Silas C. Swallow for the nomination with 380 delegates to 320 on June 28, 1900.

In 1903, a monument of Johnson was created in Newton with former Prohibition presidential candidate John G. Woolley, former Representative George W. Fithian and national Prohibition chairman Oliver W. Stewart were at the ceremony.