This photograph shows (from left to right) General Robert Baden-Powell (1857–1941), the founder of the Boy Scouts, together with the 27th President of the United States, William Taft (1857–1930), and the British lawyer, historian and Liberal politician James Bryce (1838–1922). The photograph was taken at the occasion of Baden-Powell's visit to the White House which was also attended by Bryce, the British ambassador to the United States at the time. Baden-Powell ended his military career in 1907 and began to dedicate most of his time to the promotion of the Scout movement. He published the first book on the movement, Scouting for Boys, in six instalments in 1908.
Robert Baden-Powell, William Taft, James Bryce; black-and-white-photograph, 1911, photographer: Harris & Ewing; source: Library of Congress, Prints and Photographs Division, http://hdl.loc.gov/loc.pnp/hec.00611, public domain.