The development of the explosive shell gun in the mid-1800s made the use of armor inevitable, despite its cost and weight, and armored cruisers began to appear in all navies.
The first armored cruiser was French Dupuy de Lome, started in 1888, entered service in 1895. In the same year, the Russian Ryurik entered service. Armored cruisers from 19th/20th century had usually displacement of 9,000 - 12,000 tons, speed of 18 - 20 knots. This class reached its summit in 1906-1908. Their displacement reached 14,000 - 16,000 tons then, speed - 22 - 23 knots. Since 1908 however, the building of armored cruisers stopped. It was found that their armor and guns were too weak to fight with the newest battleships - dreadnoughts, while they had almost no speed advantage above dreadnoughts. The main features of armored cruisers, like heavy guns and greater speed, than battleships, appeared again in the new class of battlecruisers (seems, that armored cruisers were the same for pre-dreadnoughts, as battlecruisers for dreadnoughts).
Typical armament of armored cruisers were 2 or 4 big calibre guns, usually 8 in - 10 in (203 - 254 mm) and some dozen guns calibre 6 in (152 mm) or similar. For example, Russian Ryurik (1895) had 4 guns 203 mm, 16 guns 152 mm and 6 guns 120 mm; French Victor Hugo (1904) had 4 guns 194 mm and 16 guns 164 mm. The British HMS Monmouth was an exception with weak armament of only 14 guns 152 mm. The last armored cruisers had stronger armament, like the British HMS Warrior (1907) - 6 guns 234 mm and 4 guns 190 mm; the German SMS Blucher (1909) - 12 guns 210 mm and 6 guns 150 mm, while the Russian Ryurik (II) (1909, British-built) had 4 guns 254 mm, 8 guns 203 mm and 20 guns 120 mm. The strongest were Japanese crafts, like Ibuki (1909) with 4 guns 305 mm (12 in), 8 guns 203 mm and 14 guns 120 mm.
Armored cruisers were the chief combatants in two naval battles: the Battle of Ulsan in the Russo-Japanese War, and the Battle of Coronel in World War I, and played important supporting roles in other battles of the period. On the other hand, these battles, as well as Battle of the Falkland Islands and battle of Jutland showed, that their armor was insufficient against battleships, and even against other armored cruisers.
The first armored cruiser of the United States Navy was the USS Maine, whose explosion in 1898 triggered the Spanish-American War. Launched in 1889, she had 7-12 inches of armor around the sides ("belt armor"), and 1-4 inches on the decks. She was redesignated as a "second class battleship" in 1894, an awkward compromise reflecting slowness compared to other cruisers, and weakness versus the first-line battleships of the time.
The New York (Armored Cruiser No. 2), launched in 1895, was less weighty than the Maine, with 3 inches of belt armor, and 3-6 inches of deck armor. Brooklyn (Armored Cruiser No. 3) was an improved version of the New York design.
Shortly after the Spanish-American War, the Navy built six Pennsylvania-class armored cruisers, almost immediately followed by five of the Tennessee class.
On 17 July 1920, all existing US armored cruisers were merged with protected cruisers in a single class "cruiser" with hull classification symbol "CA" (not to be confused with the later use of the "CA" for heavy cruisers), bringing to an end the use of the term in the US.Armored cruisers in the US Navy