Marines
2 of the 7 encyclopedias on this shelf carry an entry for Marines. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
troops enlisted for service either on board ship or on shore. They are drilled, disciplined, clothed, equipped, and paid pa similarly to the land forces. Their duties are to maintain the necessary guards, man some of the guns, form part of the armed crews of the various boats when called away for service, and form a permanent force for landing with ④ 6 Jeom 12 MARINE CORPS INSIGNIA 9. First Sergeant 6. 1st Lieutenant (Silver Bar); 2d 10. Gunnery Sergeant Lieutenant (Gold Bar) 11. Sergeant 12. Corporal the seamen if necessary. In all these matters they are commanded by their own officers. The marines of the European continental nations are not designed for service permanently on board ship; the American navy is the only one besides that of England in which the marine forms a necessary and definite fraction of ship's company. United States marines distinguished themselves in the World War. First on June 6, 1918, when they helped the French check the German advance near Château-Thierry and advancing 2 miles on a 3-mile front, captured and held Torcy and Bouresches against strong counter-attacks. In the Battle of the Oise, June 10-11, they captured a German strong point, Belleau Wood.
Aiton's Encyclopedia (1910)
ma-renz', in the British and American navies, sea soldiers,--bodies of infantry trained to accompany ships of war for the purpose of making a landing or performing such military service on shore as may require disciplined troops. Marines are commanded by their own officers and are not assigned permanently to any particular ship. The pay and discipline are similar to that of the infantry. The United States marine corps is enlisted by the navy department and is subject to naval control. It consists of 222 officers and 6,821 men, commanded by a brigadier-general. The corps gave a good account of itself in the Cuban War and in the expedition of 1900 to rescue Pekin from the Boxers. As the marines are supposed to know little of seamanship, they are the butts of the sailors' jokes. "Tell that to the marines," has passed into a popular saying, denoting incredulity.