Yaƙin Pharsalus shine ƙaƙƙarfan yaƙin yakin basasar Kaisar da aka yi a ranar 9 ga Agusta 48 KZ kusa da Pharsalus a tsakiyar Girka.Julius Kaisar da abokansa sun kafa gaba da sojojin Jamhuriyar Roma a karkashin jagorancin Pompey.Pompey ya sami goyan bayan yawancin Sanatocin Romawa kuma sojojinsa sun fi yawan sojojin sojojin Caesaran.Jami'ansa sun matsa masa lamba, Pompey ya yi yaƙi da rashin son rai kuma ya sha kashi sosai.Pompey, ya yanke kauna daga shan kashi, ya gudu tare da masu ba shi shawara a ketare zuwa Mytilene kuma daga nan zuwa Kilicia inda ya gudanar da majalisa na yaki;a lokaci guda, Cato da magoya bayan Dyrrachium sun yi ƙoƙari na farko don ba da umarni ga Marcus Tullius Cicero, wanda ya ƙi, ya yanke shawarar komawa Italiya.Daga nan suka sake haduwa a Corcyra suka tafi Libya.Wasu, ciki har da Marcus Junius Brutus ya nemi gafarar Kaisar, yana tafiya a kan wuraren daji zuwa Larissa inda Kaisar ya marabce shi da alheri a sansaninsa.Majalisar yakin Pompey ta yanke shawarar guduwa zuwaMasar , wadda a shekarar da ta gabata ta ba shi taimakon soja.Bayan yakin, Kaisar ya kama sansanin Pompey kuma ya kona wasikun Pompey.Sannan ya sanar da cewa zai gafarta wa duk wanda ya nemi rahama.Sojojin ruwan Pompeian a Adriatic da Italiya galibi sun janye ko kuma sun mika wuya.