A Message to Garcia is Hubbard's most famous and widely distributed essay written in 1889, expressing the value of individual initiative and conscientiousness in work. In it, he argues that the greatest hero is the man who simply does his job, completing the task no matter what the obstacles. As its primary example, the essay uses a dramatized version of a daring escapade performed by an American soldier, 1st Lt. Andrew S. Rowan, just prior to the Spanish–American War. The essay describes Rowan carrying a message from President William McKinley to "Gen. Calixto García, a leader of the Cuban insurgents somewhere in the mountain vastness of Cuba—no one knew where".

Within Hubbard's lifetime, the Message was reprinted more than any book besides the Bible. Today, it is required reading at U.S. military academies.