[4] Fletcher joined Theodore Roosevelt's Rough Riders as a private in Troop K.[5] He served in the U.S. Army, both in Cuba and in the Philippines for two years.

[2] After returning from the Philippines, he entered the diplomatic service under President Roosevelt's administration as secondary secretary of the United States legation in Havana, Cuba.

[6] He was in that position until 1914, by which time the mission had been raised to the status of an Embassy, making him the first United States Ambassador to Chile.

[8][9] In 1916, President Woodrow Wilson appointed him United States Ambassador to Mexico, his term coinciding with the height of World War I.

The note was intercepted in Washington and made public and is considered one of the immediate causes for the United States entering the war six weeks later.

In 1923, he was sent to the Pan-American Conference in Santiago, taking the place of Secretary of State Charles Evans Hughes, who had declined to go.