Why did the narrow battlefield make it difficult for French knights to fight at Agincourt?

At the Battle of Agincourt, the narrow battlefield significantly disadvantaged the French army by restricting their ability to maneuver and overwhelm the English ranks.1

Because the field narrowed at the English end, the French knights became so tightly packed as they advanced that they were unable to use their weapons effectively. This congestion prevented the French from utilizing their superior numbers, as the limited space forced them into a dense formation that hindered their combat effectiveness. Consequently, the terrain allowed the smaller English force to hold their position and eventually turn the tide of the battle.1