There are some obvious similarities between the deaths of Brutus and Cassius. Both die on the field of battle, having been forced into retreat, and both regard death as vastly preferable to being taken alive by the enemy. Their manner of death is also similar as they ask a subordinate to help end their lives by the sword. And both invoke Caesar at the moment of death.
However, there are also important differences. One is the state of mind in which each man meets his demise. Although both are in retreat by the end, Brutus does earlier score significant success against Octavian’s forces while Cassius is beaten back by Antony. Cassius’s own failures incline him to believe the worst, so that he fatally misinterprets events, thinking that his friend Titinius has been captured when in reality he has met up with friends. He determines to die there and then, and asks his slave Pindarus to kill him. Titinius arrives back on the scene only when it is too late.
Cassius, then, dies in a fog of uncertainty and in a mood of deep pessimism, if not quite despair, and with no-one but his slave by his side. Brutus, by contrast, goes to his death surrounded by friends:
My heart doth joy that yet in all my life
I found no man but he was true to me. (V.v.34-35)
While Cassius laments that ‘My sight was ever thick’ (V.iii.21) – an observation that can be taken figuratively as well as literally - Brutus still confidently believes in his own clear vision for Rome. He also is confident that he will gain even greater prestige by his death:
I shall have glory by this losing day
More than Octavius and Mark Antony
By this vile conquest shall attain unto. (V.v.36-38)
This is in stark contrast to Cassius:
O coward that I am, to live so long,
To see my best friend ta’en before my face! (V.iii.33-34)
The reaction to the deaths by the victors, Octavius and Antony, also shows a contrast. Antony states unequivocally that Brutus was the only noble one among the conspirators, while the others acted only from ‘envy’ (V.v.68-69). We saw earlier in the play that Cassius did indeed act from jealousy of Caesar while Brutus was motivated by his political idealism.
Brutus, then, dies as he has lived, still preoccupied with thoughts of glory and honour, still believing that his actions were entirely right. However, he also shows signs of the moral dilemma that he agonised over throughout the play, declaring that he is happier to kill himself than he ever was to kill Caesar:
Caesar, now be still;
I killed not thee with half so good a will. (V.v.50-51)
Cassius, in his death, seems to gain in stature; although he himself doesn’t seem aware of it he dies in quite a noble and dignified manner. At the end, he appears a wholly different character from the devious, calculating malcontent of the play’s opening scenes.