The English king sends to the French king a reminder of tribute due. The French king says our king is too young to be a threat and sends tennis balls instead. Our king takes an army, excluding married men and widows' sons, and succeeds against the French
The career of Henry V marked the high point, for the English, of the Hundred Years' War (which lasted from 1437 to 1453, more or less, although with frequent truces). The death of Henry almost instantly turned the course of the war around. In 1435 the French recaptured Paris, in 1450 they retook Normandy, and in 1451-1453 they threw the English out of Guyenne, which they had ruled since 1154. Except for Calais (which the English held for another century), the invaders had been driven from France.
It might be noted that, under English law, the king of England was also the rightful king of France. (Of course, there is the minor detail that Henry V was not the rightful king of England.) The French, however, managed to dig up a law that said that the throne of France could only be passed on through a male line -- and the English monarchs claimed the French throne through a female line.
The story about the tennis balls is widely told (including in some old chronicles), but there is no real reason to believe it true. Some have suspected that it derives from a story of Darius III of Persia and Alexander the Great: Darius send Alexander children's toys.
In any case, it wasn't modern lawn tennis back in the fifteenth century; modern tennis is a nineteenth century invention, based only very loosely on the older game of Court Tennis (or Royal Tennis, or Real Tennis). - RBW