Edward III’s youngest sister was called Joan of the Tower. She died in September 1362 at Hertford Castle four years after her mother died. They were both buried in Greyfriars Church in London. She spent the last years of her life living with her mother Queen Isabella (the one who got the She-wolf nickname thanks to deposing her husband and allegations of red hot pokers.) Edward III mourned for his sister and paid every year to commemorate her passing.
Joan, the daughter of Edward II and Isabella of France was seven when she married the son of Robert I of Scotland. The aim was to bring the Scottish Wars of Independence to a close with a treaty and a royal marriage. For the Scots it was an opportunity to be recognised as independent. In 1328 a border was recognised and negotiations for a royal wedding started in earnest. David was three years younger than Joan so the marriage would not be a true one until David reached the age of fourteen. If the marriage wasn’t consummated then the terms of the treaty were void – the treaty also stipulated that replacements could be founding the event of the death of the happy couple. What could possibly go wrong?
The treaty was signed by the English at Northampton in May 1328, the Scots having already signed it in Edinburgh. Queen Isabella and Roger Mortimer were behind the treaty so perhaps it’s not a surprise that Edward III didn’t hurry north when his mother and sister went to Berwick where the groom was waiting – though his father Robert I was also absent. After the wedding Joan travelled to Scotland with her new family. Joan gained the name ‘make peace’ which wasn’t necessarily complimentary. The treaty was seen as the cowardly option.
It was two years before Edward III was able to take control of his own kingdom. Edward pursued different policies from his mother and her lover. He supported Edward Balliol’s claim to the Scottish kingdom rather than his own brother-in-law’s simply because he wa snot happy at having conceded independence to the Scots and he thought that the Balliol claimant would accept English overlordship. Needless to say Edward III’s interference in Scottish politics had an effect and before long Edward Balliol was king. King David’s forces gathered against Balliol and he was forced to flee to England. In July Edward III took an army north and on the 19 July 1333 fought the Battle of Halidon Hill. Sir Archibald Douglas’s army was defeated. Archibald was the Guardian of the Realm during David’s minority. To cut a long story short Balliol did homage to Edward III and recognised the English as Scottish overlords.
Moving swiftly on – King David and Joan were sent for their own safety to France. Philip IV was Joan’s cousin once removed. There remained there from 1334 until 1341 when Balliol lost power. Unfortunately David did not know how to rule. He had received no training so there was the usual faction fighting. To make matters worse, Edward III was now waging the Hundred Years War and won the Battle of Crecy in August 1346 triggering a Scottish invasion of England thanks to a Franco-Scottish treaty dating from 1295.
On 17 October 1346 the Scots lost the Battle of Neville’s Cross and King David was taken prisoner. He spent the next eleven years in England. Joan’s position was now more difficult than ever. She had insufficient funds. Queen Isabella provided her with clothes. She was effectively a hostage for the safekeeping of David although history knows that a safe conduct was issued for her to visit David at Windsor in 1348.. To make matters worse – if possible- David fell in love with Katherine Mortimer during his captivity. When he was allowed to return to Scotland he took Katherine with her. Joan packed her own bags and came home when she was issued with another safe conduct from her brother. Edward III gave his sister and annual pension.
The image comes from Froissart’s Chronicles
The Black Prince, Edward of Woodstock, did not get married until 1361 when he was thirty.  He chose to marry his first cousin once removed – Joan of Kent who was a few years older than him.  She had already been married twice before, once bigamously.  The pair married and had two children: Edward of Anglôume born in 1365 who died when he was five and Richard of Bordeaux born in 1367.
John’s wealth and title came from his marriage to the co-heiress Blanche of Lancaster. Her father had been the 1st Duke of Lancaster but on his death with no male heirs the title died out. When John married Blanche he was given the title earl and through Blanche half of the Lancaster wealth. Blanche’s sister died in 1362 without children – the Lancaster wealth now all came to John. Â On the same day that Lionel received his dukedom from his father the dukedom of Lancaster was resurrected for John. Â Because the dukedom had been dormant and Edward III resurrected it John of Gaunt was also known as the 1st Duke of Lancaster (why would you want things to be straight forward!). Â John married three times – firstly to Blanche who was descended from Henry III via his second son Edmund Crouchback; secondly to Constanza of Castile by whose right John would try to claim the crown of Castile and thirdly to his long time mistress Kathryn Swynford with whom he had four illegitimate children surnamed Beaufort who were ultimately legitimised by the Papacy and by King Richard II.
In 1415 there were about 78 peel or pele towers in Northumberland.  These towers were essentially private fortifications for protection in the event of Scottish raids – or neighbours you  didn’t necessarily agree with.  The idea was that you could secure your family and portable valuables until it was safe to emerge or help arrived – beacons were kept on the top of the towers which could be lit to summon help and to worn the surrounding countryside of danger. 
Yesterday’s post covered all of points 1-3 and most of 4:
He and Elizabeth of Lancaster had three sons. Â The eldest and youngest died without heirs whilst the middle son, conveniently called John regained the dukedom from Henry V following the victory at Agincourt. Â John, the second Duke of Exeter, married the widow of Edmund Mortimer and had two children. Â The boy was called Henry and he was born in 1430 so we have now arrived at the Wars of the Roses generations.