According to the Iliad, Odysseus brought 12 ships to Troy. The figure appears in Book 2, the famous Catalogue of Ships, where Homer lists the Greek contingents, their commanders, the places they represented, and the number of vessels assigned to each.
Odysseus leads the Cephallenians, a coalition associated with Ithaca, Neritum, Crocylea, Aegilips, Zacynthus, Same, and the mainland opposite the islands. Homer calls Odysseus exceptionally wise in counsel and then states that twelve red-prowed ships followed him. The number describes his contingent, not the entire Greek fleet.
That distinction causes frequent confusion. The Catalogue lists roughly 1,186 Achaean ships in total, with much larger forces assigned to leaders such as Agamemnon and Menelaus. The Odyssey also begins with Odysseus’ fleet of twelve ships, but his crews are gradually lost during the homeward voyage. Thus, 12 is the Iliad’s standard answer for the fleet he led to Troy, while larger numbers belong to the Greek army as a whole or to other commanders.