The English army at Agincourt was divided (largely) into three positions: Henry V in the center, then Camoys and the Duke of York on the sides. One of the most famous English casualties of the battle was Michael (III) Earl of Suffolk. In which division was he fighting? I've been trying to hit up all the big Agincourt resources, but I'm not turning up anything.
According to Plantagenet Ancestry: A Study In Colonial And Medieval Families, 2nd Edition . Michael(III) Earl of Suffolk was a commander of the Rear Guard of the Kings Army, from September through October 1415.
According to the wiki entry he was born 1394, died 25 October 1415, so was not exactly a seasoned commander, having inherited his title only 7 weeks earlier. Wiki mentions his command:
He brought 20 men-at-arms and 60 archers to France in 1415, in company with his father, who died at the Siege of Harfleur.
If you are looking for location, the rearguard was located on the left, according to this site:
The English were drawn up into three divisions known as battles, with the vanguard commanded by Edward, duke of York, placed on the right, the mainguard by the king himself in the centre, and the rearguard by Thomas, Lord Camoys on the left.
As I understand it, we know the positions of very few of the participants at the Battle of Agincourt. There is even some considerable debate about exactly how the English army was arranged on the field (we don't even know exactly where the battle was fought!).
I just did a quick check in the index of Anne Curry's The Battle of Agincourt: Sources and Interpretations (in my opinion, one of the best resources for researching the battle) for references to the Earl of Suffolk. Perhaps the closest to suggesting his position during the battle is a quote from the Liber Metricus de Henrico Quinto (Metrical Life of Henry V), written by Thomas Elmham in about 1418 - just 3 years after the battle - on page 47:
Here the Duke of York was overcome by the whirlwind of war. The king washed his body for burial with royal care. The young Earl of Suffolk died there also. Scarcely thirty other English died by the sword.
This might be taken to suggest that the Earl was fighting with the Duke of York. Equally, it might simply be observing that both the Duke of York and the Earl of Suffolk fell at Agincourt.
This is actually a good example of why it is so difficult to state many details of the period with certainty.