In which play by William Shakespeare is the St Crispin Day speech given?

The St Crispin's Day speech is a part of William Shakespeare's 1599 history play "Henry V", Act IV Scene iii 18–67. On Saint Crispin's Day, just before the the Battle of Agincourt, King Henry V urged his men, who were vastly outnumbered by French forces, to recall how the English had previously won great battles against the French. The king called his men a "band of brothers" and told them that if they acted in total unity (one in spirit) they could inflict a great defeat upon their enemy.

In the play "Henry V", it tells the story of King Henry V of England. The play focuses on events immediately before and after the Battle of Agincourt (1415), during the Hundred Years' War. Shakespeare has precisely told the story of a king who as a young man has matured. The English king embarked on an expedition to France and, his army badly outnumbered, defeats the French at Agincourt on Saint Crispin's Day. The day is a feast that falls on October 25th, noting the deaths (beheadings) of the Christian saints Crispin and Crispinian, twins who were martyred c. 286 AD.