Can you give me some background on John of Gaunt?

Question

How did he inherit the crown and how did Henry inherit it from him?

Answer 1

Ah, Google Books to the rescue, a nice 1904 publication by Sydney Armitage-Smith.

Answer 2

John of Gaunt was the fourth son of King Edward III and Queen Philippa; he was born in 1340 in Ghent - or Gaunt.

His first wife was Blanche of Lancaster and, on the death of her father, he advanced to the Duchy of Lancaster. On her death, he married Constance, daughter of the King of Castile and Leon. When this lady died, he married his long-term mistress, Katherine Swynford (sister of the poet Chaucer's wife) and had their children legitimized. They were the first of the Beaufort line.

However, he was never King of England himself. His son by Blanche, Henry Bolingbroke, usurped the crown of Richard II, and became Henry IV.

You can read more details below.

Answer 3

http://en.wikipedia.org/wiki/John_of_Gaunt