San Francisco Directory for 1867 lists Stewart Blanc as a bootmaker; 1904 Directory lists a Stewart A. Blanc, clerk. Judge McKenna is possibly Joseph McKenna (1843-1926), who served as a Calif. state assemblyman, 1875-77; U.S. Representative from Calif., 1885-1892; Judge of the U.S. Court of Appeals, 1892-1897; U.S. Attorney General, 1897-1898; and Justice of the Supreme Court, 1898-1925. General Benjamin Harrison probably refers to the 23rd president of the United States, 1889-1893, who was a brigadier general in the Civil War.
From the description of Stewart A. Blanc miscellany : 1867-[1918?]. (California Historical Society). WorldCat record id: 122550301