At the funeral speech, how did Marc Antony explain that Caesar was not "ambitious"?

In Act 3.2 of Shakespeare's Julius Caesar, Antony juxtaposes (places in opposition) an unambitious act performed by Caesar, with a refrain about Brutus's (or the other conspirators') belief that Caesar was ambitious and about Brutus (or the other conspirators) being honorable men.  I'll put it in bullets:

• Caesar did an unambitious act


• But Brutus says he was ambitious


• And Brutus is an honorable man

Here's an example from Antony's speech, with the quotes in bullets:

• I thrice presented him a kingly crown,/Which he did thrice refuse.  Was this ambition?


• Yet Brutus says he was ambitious,


• And sure he is an honorable man.  (Act 3.2.105-108)

Antony uses irony to persuade the crowd that Caesar was not ambitious and was therefore assassinated unjustly, because he earlier promises Brutus that he will not directly say anything negative about the conspirators.  He, therefore, says only positive things about the conspirators, but the juxtaposition of Caesar's unambitious acts with those positive things, creates irony. 

And it also creates a mob that riots through Rome looking to kill the conspirators.