Christopher Marlowe translated several classical works from Latin into English, including the first book of the incomplete ten-book Pharsalia, an epic by the first-century poet Marcus Annaeus Lucanus (known as Lucan). While it is not known for certain the date of Marlowe's translation, it first appeared in print in 1600. It is a safe assumption that he probably translated this first book near the end of his life (1593), since it was left unfinished. The original poem is an epic about the first-century-B.C. Roman civil war, and the poem contains sufficient references to Marlowe's own time to provide some apt comparisons to Tudor England. Marlowe was Lucan's first English translator, and his choice of Lucan may hint at the Elizabethan poet's Republican sympathies.

Lucan gives us the background of the war, and in Marlowe's spare and headlong blank verse Lucan's passionate partisanship and hatred of war comes through: "Roome if thou take delight in impious warre, / First conquer all the earth, then turne thy force / Against thy selfe: as yet thou wants not foes" (lines 21-23). Marlowe may have heartily agreed with this sentiment, as the civil war in England was in the not-so-distant past.

The first book concerns the movements of Julius Caesar, who has returned to Italy from his conquests and waits in the north above the river Rubicon.  Crossing the Rubicon was an act of war on Rome for a Roman general at the head of his army, so Caesar is pleaded with by the Spirit of Rome to not make war on his countrymen. But Caesar is ambitious, and he hates his rival general and Senator Pompey, so he historically crosses the river and thus ensures that Rome, at the head of a great empire, will now be embroiled in civil war.

The poet bewails the fact that if Roman had not fought Roman, then "Ay me, O what a world of land and sea / Might they have won whom civil broiles have slaine." After Caesar crosses the river, he announces his intentions to take over Rome: "An end of peace; here end polluted lawes; / Hence leagues, and covenants; Fortune thee I follow, Warre and the destinies shall trie my cause."  Curio, a sometime tribune, joins his cause. The citizens in Rome learn of these events, and there are supernatural portents of doom and general panic in response.