Near the end of Caesar's reign, he began to consolidate his power. He continued this until 44 B.C.E., when he elected himself dictator for life. This act, along with his continuous attempts at gaining more and more power, turned much of the Senate against him. Sixty members of the Senate came to the the same conclusion. The only resolution was to assassinate Caesar.
The following words are taken (not literally, but as a source) from Nicolaus of Damascus, who wrote an account of Caesar's murder.
After many proposals of how and when to assassinate Caesar, they decided to kill him while he sat in the Senate, where he would be by himself, as no non-Senators were allowed in the Senate. They could also conceal their daggers this way.
Caesar's friends were alarmed at the rumors going around and tried to convince him to stay. They also argued that since he was having a dizzy spell, and since Calpurnia (Caesar's wife) had bad dreams the night before concerning Caesar, that he should stay and tell the Senate he was ill. Brutus then assured Caesar that he would be fine, and that he should have courage. Since Caesar still believed Brutus to be his friend at the time, he accepted and decided to attend. Before Caesar entered the chamber, the priests brought out the sacrifices, which clearly showed unfavorable results for Caesar. This told that there were malignant spirits hidden in the room. Caesar took this excuse to wait to hold the Senate the next day. However, when attendants came to inform him that the Senate was full, and when Brutus once again swayed Caesar's view, he decided to attend.
Under the pretext of a request for his brother (whom Caesar exiled), Cimber approaced and grasped Caesar's toga. This was the signal, and many quickly unsheathed their daggers and attacked. At 35 wounds, Caesar let out his last breath. The leader had fallen.