Toward the end of the play, when the conspirators are on the run and the battle has been lost, Cassius commits suicide rather than be taken prisoner. More specifically he has his friend, Pindarus, do the deed for him:
[Above] Titinius is enclosed round about
With horsemen, that make to him on the spur;
Yet he spurs on. Now they are almost on him.
Now, Titinius! Now some light. O, he lights too.
And, hark! they shout for joy.
Come down, behold no more.
O, coward that I am, to live so long,
To see my best friend ta'en before my face!
Come hither, sirrah:
In Parthia did I take thee prisoner;
And then I swore thee, saving of thy life,
That whatsoever I did bid thee do,
Thou shouldst attempt it. Come now, keep thine oath;
Now be a freeman: and with this good sword,
That ran through Caesar's bowels, search this bosom.
Stand not to answer: here, take thou the hilts;
And, when my face is cover'd, as 'tis now,
Guide thou the sword.
[PINDARUS stabs him]
Caesar, thou art revenged,
Even with the sword that kill'd thee.
Rather than throw himself on his own sword, Cassius gives his sword to Pindarus and tells him to do it (kill Cassius, not himself).
Trivia - There is a line in Macbeth where, chased by his enemies and looking like all is lost, Macbeth says, "Why should I play the Roman fool, and die on mine own sword?" This is the sort of "honorable" action that he's referring to.
30 May '11, 08:33