|Irish Republican Brotherhood.See Irish Republican Army.|
|Irish War of Independence (1918–1921). A guerrilla campaign for Irish independence that effectively became the first war of national liberation of the twentieth century. It was sparked in part by a British decision to execute the leaders of the Easter Rising, thus making them nationalist martyrs. Its main source was anger over the unfinished business of granting Home Rule to Ireland, postponed since before World War I. It began when Sinn Féin members of Parliament met in Dublin rather than Westminster, claiming to represent an independent Ireland. The British responded with arrests and detentions. The campaign was sporadic, but escalated during 1919–1920 with ambushes and assassinations by the Irish Republican Army, led brilliantly by Michael Collins (among others). British reprisals were often harsh, and both sides committed atrocities. Murders by less-than-disciplined, irregular forces such as the Black’n Tans turned a passive public in favor of the IRA, whereas British opinion soon tired of the war—coming as it did so soon after the Great War of 1914–1918. The conflict ended with the 1921 Anglo-Irish Treaty, which partitioned Ireland between Ulster and the Irish Free State. That settlement divided the IRA, however, which in turn gave rise to the brief Irish Civil War. See also Lloyd George; Eamon de Valera.|
|ironclad. Any wooden warship using armor plating—literally “clad in iron”—to protect against incoming ordnance. The Koreans built ironclads in the sixteenth century (the famous “turtle ships” that met Hideyoshi’s invasions), but the term usually refers to the mid-nineteenth century ships that ushered in a revolution in military affairs by rendering all wooden ships instantly obsolete. Russia employed iron-clad ships in the Crimean War that inflicted great damage on a wooden enemy fleet. France built the first ironclad, La Gloire, that had a wooden hull bound with iron. Britain built the first fully iron-hulled ship, the HMS Warrior, a steam-powered vessel launched in 1861. Its design was revolutionary in other ways as well: it had armored decks, breech-loading and rifled guns with a range of almost three miles, and replaced coal power with oil turbines that made it the fastest warship of the day. France followed suit and then Russia. These three nations remained the main naval competitors for several decades. The CSS Virginia (built on the salvaged hull of a U.S. frigate, the Merrimack) was launched by the Confederacy on March 8, 1862. It savaged the wooden ships of the Union blockade line off the Virginia coast until met in battle the next day by the USS Monitor, in the first-ever all-ironclad contest. This was inconclusive, as neither side had armor-piercing shells—with no need for these previously, they were not in-|
vented yet—meaning both ships were unsinkable by bombardment, though highly susceptible to inclement weather. The Monitor was the first warship to employ turret-mounted guns, which made it necessary to turn only the gun, not the ship; this quickly replaced broadside and raking tactics, and soon turrets were mounted on all warships. The Union later outbuilt the South, assembling an ironclad fleet of “monitors” by war’s end. Other naval powers noted the overnight obsolescence of their fleets and quickly converted to all-iron ships. The next stage in naval evolution came 45 years later, with the Dreadnought.