Henry VI (6 December 1421 – 21 May 1471) was King of England from 1422 to 1461 and again from 1470 to 1471, and disputed King of France from 1422 to 1453. Until 1437, his realm was governed by regents. Contemporaneous accounts described him as peaceful and pious, not suited for the dynastic wars, such as the Wars of the Roses, which commenced during his reign. His periods of insanity and his inherent benevolence eventually required his wife, Margaret of Anjou, to assume control of his kingdom, which contributed to his own downfall, the collapse of the House of Lancaster, and the rise of the House of York.
More information on the Wikipedia page [1]: there is much coverage elsewhere.