iron

iron often in figurative use to mean stern and unyielding.
iron age originally the Greek and Roman poets' name for the last and worst period of human history, succeeding the gold, silver, and brazen ages; in allusive reference, an age of wickedness, cruelty, or oppression.

In archaeology, the Iron Age denotes a prehistoric period that followed the Bronze Age, when weapons and tools came to be made of iron. It is conventionally taken as beginning in the early 1st millennium bc, but iron-working began with the Hittites in Anatolia in c.1400 bc. Its arrival in Britain was associated with the first Celtic immigrants in about the 6th century bc. In much of Europe it ended at the Roman period, but outside the Roman Empire it continued to the 4th–6th centuries ad.
Iron Chancellor the nickname of the German statesman Otto von Bismarck (1815–98), Chancellor of the German Empire (1871–90). In recent times it has been applied to the British Chancellor of the Exchequer, Gordon Brown.
Iron Cross the highest German military decoration for bravery, originally awarded in Prussia (instituted 1813) and revived by Hitler in 1939.
Iron Crown of Lombardy the hereditary crown of the ancient kings of Lombardy, so called from having a circlet of iron inserted, reputed to have been made from one of the nails of the Cross.
Iron Curtain a notional barrier separating the former Soviet bloc and the West prior to the decline of communism that followed the political events in eastern Europe in 1989. The phrase is particularly associated with a speech by Winston Churchill in 1946, ‘From Stettin in the Baltic to Trieste in the Adriatic an iron curtain has descended across the Continent,’ although the term in relation to the Soviet Union and her sphere of influence is recorded intermittently from 1920.
Iron Duke a nickname of the Duke of Wellington (1769–1852), recorded from the mid 19th century.
the iron entered into someone's soul someone has become deeply and permanently affected by imprisonment or ill-treatment. It comes from the Latin ferrum pertransit animam ejus, a mistranslation in the Vulgate of the Hebrew, literally ‘his person entered into the iron’, i.e., he was placed in chains or fetters.
iron hand in a velvet glove ruthlessness disguised by courtesy; recorded in Carlyle's Latter-day Pamphlets (1850) as defined by Napoleon.
Iron Lady the nickname of Margaret Thatcher (1925– ), given her in January 1976 by the Soviet defence ministry newspaper Red Star, which accused her of trying to revive the Cold War.
iron mask that worn by the Man in the Iron Mask, a political prisoner in France at the time of Louis XIV, said by some to be a brother of the king, who was made to wear a mask supposedly of iron; he died in the Bastille in 1703, and his identity is still disputed.
iron triangle a grouping of three power bases for mutual defence and support, as for example the Pentagon, the defence industry, and Congress.

See also blood and iron, rule with a rod of iron, strike while the iron is hot.