In March 1864 he visited the scene of the Prusso-Danish war, and distinguished himself at Dybbol by sallies from the Danish redoubts for the purpose of rescuing the wounded. As a recognition of his bravery he was made a knight of the Order of the Dannebrog. His impressions of the campaign were recorded in his letters to his mother published under the title "The Danes in Camp" (1864). He went to the United States during the American Civil War, and he witnessed the Siege of Richmond (1864–65). During the Franco-Prussian War he went to France, and was present at the Battle of Sedan (1870). He was outside Paris during the Siege of Paris (1870–71), and was one of the first to enter the city after the capitulation, being nearly shot as a spy on his way in. He remained there during the Paris Commune in the company of his second brother, Alan Herbert, who practised medicine in Paris. In later life he received the Austrian Order of the Iron Crown, third class, for helping to rescue the crew of the "Pare", an Austrian vessel wrecked off Westward Ho!