A major battle of The Hundred Years War, it was fought on September 19, 1356 - near Poitiers, France. English Prince Edward (of Wales), the dreaded "Black Prince", had begun a series of "scorched earth" raids throughout France. Leading a predominately "horse force", the raids were particularly effective in eliminating his enemy's (France), resources/supplies. However, upon reaching the fortifications at River Loire in Tours - Edward found this obstacle a bit too hard to raze. This delay in his "hit and run" tactics gave the French King John II time to catch up to Edward. Removing around 20,000 of his infantry and lesser troops from his army, John headed north towards Tours. As was the Medieval custom, negotiations were entered into. Not going well (The Battle of Crecy still fresh in the minds of the French), the battle would "be joined" (as to the phrase!)
The French noted the English caravans leaving the area around Poitiers. Mistaking this for a retreat, the French mounted a hasty cavalry charge against the English archers. The archers began to aim at the French horse's. The front of the animals were well protected, their flanks were not. The English archers changed positions and took aim again. This time, the volley was deadly effective as hundreds of mounted French knights fell (as their mounts were hit). Undeterred by this, the French continued sending more and more troops into the English positions. Arrayed in a protective wedge formation, the English held. The French could not move them from the field. The cavalry action took 2 long hours. Next came the French infantry. Line after line they flung themselves into the English lines. Soon, the French infantry began to retreat (more so from panic and that most of their commanders had fallen). Finally, King John himself gathered his remaining forces and advanced with them. The English archers, now running low on ammunition - either joined the infantry ranks or took uninjured horses from the field, becoming a "makeshift cavalry".
The French fought hard during the final engagements. Still - unknown to them, Prince Edward had a hidden reserve force in the nearby woods. Having them outflank the French and approach upon their rear positions. King John was said to have fought to the last sword stroke. He was eventually captured by the English forces. This battle was a particular "spine snap" to the French army and Kingdom. Without effective control (no King), and King John's political back-biting Council, the Kingdom would fall into anarchy and chaos. It will be several years until the King will be ransomed back to France. Many territories will be ceded over to the English as a result. A result that will eventually lead to Agincourt in 1415.