1.The SI unit of inductance, equal to an electromotive force of one volt in a closed circuit with a uniform rate of change of current of one ampere per second.

1.(1394–1460), Portuguese prince; known as Henry the Navigator. The third son of John I of Portugal, he organized many voyages of exploration, most notably south along the African coast, thus laying the foundation for Portuguese imperial expansion round Africa to East Asia.

2.Henry I (1068–1135), youngest son of William I, reigned 1100–35. His only son drowned in 1120, and although Henry extracted an oath of loyalty to his daughter Matilda from the barons in 1127, his death was followed almost immediately by the outbreak of civil war.

3.Henry I (c.876–936), reigned 919–36; known as Henry the Fowler. He waged war successfully against the Slavs in Brandenburg, the Magyars, and the Danes.

4.Henry II (1133–89), son of Matilda, reigned 1154–89. The first Plantagenet king, he restored order after the reigns of Stephen and Matilda. Opposition to his policies on reducing the power of the Church was led by Thomas à Becket, who was eventually murdered by four of Henry’s knights.

5.Henry II (973–1024), reigned 1002–24, Holy Roman Emperor 1014–24; also known as Saint Henry.

6.Henry III (1017–56), reigned 1039–56, Holy Roman emperor 1046–56. He brought stability and prosperity to the empire, defeating the Czechs and fixing the frontier between Austria and Hungary.

7.Henry III (1207–72), son of John, reigned 1216–72. His ineffectual government caused widespread discontent, ending in Simon de Montfort’s defeat and capture of Henry in 1264. Although he was restored a year later, real power resided with his son, who eventually succeeded him as Edward I.

8.Henry IV (1050–1106), son of Henry III, reigned 1056–1105, Holy Roman emperor 1084–1105. Increasing conflict with Pope Gregory VII led Henry to call a council in 1076 to depose the Pope, who excommunicated Henry. Henry obtained absolution by doing penance before Gregory in 1077 but managed to depose him in 1084.

9.Henry IV (1367–1413), son of John of Gaunt, reigned 1399–1413; known as Henry Bolingbroke. He overthrew Richard II, establishing the Lancastrian dynasty. His reign was marked by rebellion in Wales and the north, where the Percy family raised several uprisings.

10.Henry V (1086–1125), reigned 1099–1125, Holy Roman emperor 1111–25.

11.Henry V (1387–1422), son of Henry IV, reigned 1413–22. He renewed the Hundred Years War soon after coming to the throne and defeated the French at Agincourt in 1415.

12.Henry VI (1165–97), reigned 1169–97, Holy Roman emperor 1191–7.

13.Henry VI (1421–71), son of Henry V, reigned 1422–61 and 1470–1. He was unfit to rule effectively on his own due to a recurrent mental illness. Government by the monarchy became increasingly unpopular and after intermittent civil war with the House of York (the Wars of the Roses), Henry was deposed in 1461 by Edward IV. He briefly regained his throne following a Lancastrian uprising.

14.Henry VII (1457–1509), the first Tudor king, son of Edmund Tudor, Earl of Richmond, reigned 1485–1509; known as Henry Tudor. Although the grandson of Owen Tudor, he inherited the Lancastrian claim to the throne through his mother, a great-granddaughter of John of Gaunt. He defeated Richard III at Bosworth Field and eventually established an unchallenged Tudor dynasty.

15.Henry VII (c.1269/74–1313), reigned 1308–13, Holy Roman emperor 1312–3.

16.Henry VIII (1491–1547), son of Henry VII, reigned 1509–47. Henry had six wives (Catherine of Aragon, Anne Boleyn, Jane Seymour, Anne of Cleves, Catherine Howard, Katherine Parr); he executed two and divorced two. His first divorce, from Catherine of Aragon, was opposed by the Pope, leading to England’s break with the Roman Catholic Church.

17.The name of eight kings of England.

18.The name of seven kings of the Germans, six of whom were also Holy Roman emperors.