Plutarch. Plutarch's Lives of the Noble Grecians and Romans
Englished by Sir Thomas North. Trans. Sir Thomas North. Vol. 6 (1579; London: David Nutt, 1896) 224.

MARCUS    flie, bicause they were greatly troubled for the losse of 
BRUTUS    their campe, and of them there were slayne by hand, three 
    legions. Then being very earnest to followe the chase of 
    them that fled, they ranne in amongest them hand over 
    head into their campe, and Brutus among them. But 
    that which the conquerors thought not of, occasion shewed 
    it unto them that were overcome : and that was, the left 
    wing of their enemies left naked, and ungarded of them 
    of the right wing, who were strayed too far of, in follow- 
    ing of them that were overthrowen. So they gave a hot 
    charge upon them. But notwithstanding all the force they 
    made, they coulde not breake into the middest of their 
    battell, where they founde men that received them, and 
    valliantlie made head against them. Howbeit they brake 
    and overthrewe the left wing where Cassius was, by reason 
    of the great disorder among them, and also bicause they had 
    no intelligence how the right wing had sped. So they 
    chased them beating them into their campe, the which they 
    spoyled, none of both the Chieftaines being present there. 
    For Antonius, as it is reported, to flie the furie of the first 
    charge, was gotten into the next marish: and no man coulde 
    tell what became of Octavius Caesar, after he was caried out 
Octavius    of his campe. Insomuche that there were certaine souldiers 
Caesar falsely    that shewed their swords bloodied, and sayd that they had 
reported to    slaine him, and did describe his face, and shewed what age 
be slaine at    he was of. Furthermore the voward, and the middest of 
the battell of    Brutus battell, had alreadie put all their enemies to flight 
Philippes.    that withstoode them, with great slaughter: so that Brutus 
    had conquered all of his side, and Cassius had lost all on the 
Cassius    other side. For nothing undid them, but that Brutus went 
misfortune.    not to helpe Cassius, thinking he had overcome them, as him 
    selfe had done: and Cassius on the other side taried not 
    for Brutus, thinking he had bene overthrowen, as him selfe 
    was. And to prove that the victorie fell on Brutus side, 
    Messala confirmeth it: that they wanne three Eagles, and 
    divers other ensignes of their enemies, and their enemies 
    wanne never a one of theirs. Now Brutus returning from 
    the chase, after he had slaine and sacked Caesars men: he 
    wondred muche that he coulde not see Cassius tent standing