“...if they would have used longbows if they could have sent those arrows into the German trenches what the results would have been.”
The British must have surely thought about the longbow or any weapon that could break the bloody stalemate of trench warfare.
The effectiveness of the English longbow at Crecy & Agincourt depended on massed volleying and archers’ ability to loose a fifth shaft while the first was still in the air.
The German response to a storm of incoming longbow arrows (which were heavy & meant to pierce armor) would have been from another indirect fire weapon: the trench mortar. German mortars were without peer both in size & destructive power.
But, your interesting question was about the transition from longbows to firearms. Archers were deadly at range, but other soldiers such as dragoons & infantry had to actually close with the enemy with pikes & swords. Archers took up to ten years to acquire their skill; their lives were precious on the battlefield.
Masses of footsoldiers armed with muskets & bayonets were a far more mobile force. Note that earlier generations of soldiery wore helmets & chain mail armor. These were made moot by the advent of gunpowder.
Just my thoughts. Come to think of it, the crossbow was used by commandos. Yanks used shotguns in the trenches. What’s past is prologue.
Our thoughts also. To this day, I wonder what it must have been like to be on the receiving end of a hail of arrows like that.
BTW, the French did charge with calvary at both Crecy and Agincourt and they got cut down. The remarkable thing is to look at the casualties on both side of those battles. And to look at the number of fighting men on both sides. The English were vastly outnumbered.
As to WW1, I would suppose the best way to do it is at night or early morn and when things were more quiet. And to do it with no warning at all.
Fun discussing this.