I can't imagine 700+ men(some number I saw in another thread) going willingly to their deaths. And it's not like they had firearms available like a more "modern" mass execution.
Was there resistance to this command? Did any of Henry's soldier or advisors object?
As discussed in some of my previous answers so helpfully linked by /u/DanKensington, Henry V ordered the killing of the prisoners at Agincourt primarily because he thought many of them might still be an actual threat if they tried to break free while the main French army regrouped and pressed their assault again. Henry's captains and advisors most likely would not have been able to consult on this decision, as they were strung out along the English battle line, actively fighting. Some of them were probably wounded, while one, the Duke of York was famously killed, the only major English aristocrat to have died on the field that day. Henry was also directly involved in the fighting and would not have been able to come to a more consensus-based decision even if he had wanted to. However, many soldiers in his army did object to the killings, not on the basis of morality or chivalry, but on concerns of finance. Those captives represented potentially massive windfalls and glory for their captors, while a corpse was only good for whatever jewelry might be on it.
To ensure that his order was carried out with a minimum of grumbling, Henry assigned one of his own men and a small group of archers to carry out the work. English soldiers probably had removed the helmets or visors of captured enemies, and dispatched their prisoners with quick blows of swords and daggers. Without weapons, possibly being bound, and with many wounded, the prisoners were in no state to resist and there is no known evidence that the killings were difficult due to prisoners fighting back. Some of them were probably not aware of the order until they saw an English soldier descend on them and their comrades with a blade drawn. One French soldier's recollections of the battle mention that he was wounded and locked inside a local farmhouse with other wounded men. When the order came, the English simply set the farmhouse on fire rather than go inside to kill each prisoner individually. This suggests that the English sought to divide their prisoners and had at least some thought towards securing them to make sure the prisoners couldn't escape easily or band together to escape. The killings probably were not conducted with hundreds of men being slaughtered all at once in a compact area, but small, divided groups being systematically butchered as word of Henry's cold and pragmatic order spread throughout the English ranks.
Grisly as the topic may be, if you've enough knowledge to contribute, please do so; more posts are always welcome. For the meantime, OP, that particular episode of Agincourt has come up before, and thus, we can look to u/MI13's posts:
Of course, other users have their own posts on the matter: