Leadfingers, allow me to correct your misconceptions about Agincourt.
Henry V took a marauding bunch over in the Spring and Summer 1415 - ostensibly to establish his claim to the French throne. (Incidentally, this claim was so risible that even Shakespeare derided it very funnily at the beginning of his hagiography "Henry V"). Henry and his hooligans had a good time besieging snaller towns like Harfleur and starving their citizens to death. When he heard that the French - not surprisingly - were taking exception to these activities and sending a large army to expedite his departure, what do you think he did? Did he rush to confront them, or march on Paris? The Hell he did, he bolted for Calais to get the next ferry home. Slowed down by exhaustion, lack of any more plundered supplies and dysentry, his army failed to cross the Seine in time. With woods behind him and a very large French army in front of him blocking his way to the Seine, he did the only thing he could do. He stayed where he was. It was now late October and the wrong end of the hooligan season. He prayed for the only two things which could save him. He needed rain (usually a fair bet for a Brit) and incredible stupidity on the side of the French. He got both.
In short, the French were provoked into attacking over a narrow area into thick mud into which the English had driven stakes. I am sure I do not need to explain why this was a bad idea for cavalry whose armour could be pierced at between two and three hundred metres by the longbows. So the French army was massacred on the day. And did Henrý then march on Paris?. You bet he didn't! It was all aboard the TGV for Calais and the next ferry home. When Henry landed, he bared his head and walked along in penance. He was dead two years later from dysentry.
In short, Agincourt was fought because the English had lost the campaign and were trying to run away and get back home. It was a brilliant opportunist military victory on the one hand. On the other hand, it was part of a nasty, unjust and sordid campaign which we lost. I don't think we Brits should feel so smug about it. Henry certainly did not!