Robert Lansing was born in Watertown, New York in October 1864, the son of John Lansing (1832-1907) and Maria Lay (Dodge) Lansing.
Lansing advocated "benevolent neutrality" at the start of World War I. Following the sinking of the RMS Lusitania on 7 May 1915 by the German submarine , Lansing backed Woodrow Wilson in issuing three notes of protest to the German government.