Geoffrey begins with a brief topography of Britain, expounding on its many virtues—abundance of minerals, richness of soil, well-stocked woodlands, abundant springs, rivers, and lakes. He describes the five tribes that inhabit the island: the Norman-French, Britons, Saxons, Picts, and Scots. The Britons came first but were arrogant, so God sent others to humble them.

Geoffrey explains how the Britons came to the island and from where they originated. Fleeing the fall of Troy, Aeneas travels to Italy, where he secures both the kingdom and the Italian princess Lavinia as his wife. After Aeneas’ death, his son Ascanius becomes king. He fathers Silvius, whose child, Brutus, is destined to cause his parents’ death, wander in exile, and finally “rise to the highest honor” (42). Brutus’ mother dies in childbirth. When he is 15, Brutus accidentally kills his father during a hunt with an errant arrow, leading to his expulsion from Italy, after which he wanders through Greece. There, he encounters descendants of Priam’s son Helenus who Greek king Pandrasus is holding captive. Realizing they are of the same Trojan tribe, Brutus stays among them, and his wisdom and bravery gain their trust and admiration. The Trojans beg him to lead them to freedom from the Greeks, and Brutus agrees.