Brutus believes that the men should march to Philippi to meet Antony and Octavius' army, but Cassius believes that it would be better for the enemy to come to them. For the moment, Brutus' and Cassius' army is camped upon a hill, and the enemy would have to not only march, but climb uphill to fight them. This would give their (Brutus and Cassius) army time to rest before the battle. Brutus thinks that they need to strike while the iron is hot and that it's better to march out into the open plains of Philippi and face the enemy immediately. Brutus wins the argument, in spite of Cassius' complaints, and they march to Philippi where they meet their end.
William Shakespeare's The Tragedy of Julius Caesar features two strong-willed characters, Brutus and Cassius, who attempt to form a conspiracy to oppose what they see as the increasingly tyrannical Julius Caesar.
As the post above noted, Cassius wishes to hang back and let the enemy come to them, while Brutus wants to go on the offensive.
It is significant to note that at this point in the play Cassius and Brutus have just concluded a serious argument (about whether or not Cassius was taking bribes) which nearly ended their friendship. At the end of the argument Cassius learned that Brutus had just found out about his wife Portia’s suicide.
It is possible that this makes Cassius more likely to give in to Brutus in the matter of war strategy. He knows that Brutus is grieving and less likely to be amenable to suggestions or differences of opinion than he might be otherwise.
Brutus, for all of his talk about honor, makes several tragic mistakes in judgment in this play. The first was allowing Mark Antony to speak at Caesar’s funeral. Antony turned the Roman populace against them and they had to flee. Brutus’ decision to march to the enemy will prove equally disastrous.