Question: Messapus join with whom in a battle against Aeneas and the Trojans which was described in the Greek Epic Cycle, in particular in the "Iliad"?

Context paragraphs:
Little Iliad: The Little Iliad (Greek: Ἰλιὰς μικρά , "Ilias mikra"; Latin: "parva Illias" ) is a lost epic of ancient Greek literature.  It was one of the Epic Cycle, that is, the "Trojan" cycle, which told the entire history of the Trojan War in epic verse.  The story of the "Little Iliad" comes chronologically after that of the "Aethiopis", and is followed by that of the "Iliou persis" ("Sack of Troy").  The "Little Iliad" was variously attributed by ancient writers to Lesches of Pyrrha, Cinaethon of Sparta, Diodorus of Erythrae, Thestorides of Phocaea, or Homer himself (see Cyclic poets).  The poem comprised four books of verse in dactylic hexameter, the heroic meter.

Aethiopis: The Aethiopis or Aithiopis (Greek: Αἰθιοπίς , "Aithiopis"; Latin: "Aethiopis" ) is a lost epic of ancient Greek literature.  It was one of the Epic Cycle, that is, the "Trojan" cycle, which told the entire history of the Trojan War in epic verse.  The story of the "Aethiopis" comes chronologically immediately after that of the Homeric "Iliad", and is followed by that of the "Little Iliad".  The "Aethiopis" was sometimes attributed by ancient writers to Arctinus of Miletus (see Cyclic poets).  The poem comprised five books of verse in dactylic hexameter.

Troy: Troy (Ancient Greek: Τροία , "Troia" and Ἴλιον , "Ilion", or Ἴλιος , "Ilios"; Latin: "Trōia" and "Īlium" ; Hittite: "Wilusha" or "Truwisha"; Turkish: "Truva or Troya" ) was a city situated in the far northwest of the region known in late Classical antiquity as Asia Minor, now known as Anatolia in modern Turkey, near (just south of) the southwest mouth of the Dardanelles strait and northwest of Mount Ida.  The present-day location is known as Hisarlik.  It was the setting of the Trojan War described in the Greek Epic Cycle, in particular in the "Iliad", one of the two epic poems attributed to Homer.  Metrical evidence from the "Iliad" and the "Odyssey" suggests that the name Ἴλιον ("Ilion") formerly began with a digamma: Ϝίλιον ("Wilion"); this is also supported by the Hittite name for what is thought to be the same city, Wilusa.

Acamas (son of Antenor): With his brother Archelochus and his cousin Aeneas, Acamas was lieutenant of the Dardanian contingent to assist King Priam.  Along with Aeneas and Archelochus he led one of the five divisions attacking the Argive wall in the battle for the ships.  Homer's "Iliad", Book 2.  823 describes the troops of the Dardanians and its leaders: ""The Dardanians were led by brave Aeneas, whom Aphrodite bore to Anchises, when she, goddess though she was, had lain with him upon the mountain slopes of Ida.  He was not alone, for with him were the two sons of Antenor, Archilokhos and Akamas, both skilled in all the arts of war." "While in Book 16, Acamas avenged the death of his brother, who had been killed by Ajax, by slaying Promachus the Boeotian."But he knew well who it was, and the Trojans were greatly vexed with grief [akhos].  Akamas then bestrode his brother's body and wounded Promakhos the Boeotian with his spear, for he was trying to drag his brother's body away.  Akamas vaunted loudly over him saying, "Argive archers, braggarts that you are, toil [ponos] and suffering shall not be for us only, but some of you too shall fall here as well as ourselves.  See how Promakhos now sleeps, vanquished by my spear; payment for my brother's blood has not long delayed; a man, therefore, may well be thankful if he leaves a kinsman in his house behind him to avenge his fall.""

Iliupersis: The Iliupersis (Greek: Ἰλίου πέρσις , "Iliou persis", "Sack of Ilium"), also known as The Sack of Troy, is a lost epic of ancient Greek literature.  It was one of the Epic Cycle, that is, the "Trojan" cycle, which told the entire history of the Trojan War in epic verse.  The story of the "Iliou persis" comes chronologically after that of the "Little Iliad", and is followed by the "Nostoi" ("Returns").  The "Iliou persis" was sometimes attributed by ancient writers to Arctinus of Miletus (see Cyclic poets).  The poem comprised two books of verse in dactylic hexameter.

Telegony: The Telegony (Greek: Τηλεγόνεια , "Tēlegoneia"; Latin: "Telegonia" ) is a lost ancient Greek epic poem about Telegonus, son of Odysseus by Circe.  His name ("born far away") is indicative of his birth on Aeaea, far from Odysseus' home of Ithaca.  It was part of the Epic Cycle of poems that recounted the myths of the Trojan War as well as the events that led up to and followed it.  The story of the "Telegony" comes chronologically after that of the "Odyssey" and is the final episode in the Epic Cycle.  The poem was sometimes attributed in Antiquity to Cinaethon of Sparta, but in one source it is said to have been stolen from Musaeus by Eugamon or Eugammon of Cyrene (see Cyclic poets).  The poem comprised two books of verse in dactylic hexameter.

Cyclic Poets: Cyclic Poets is a shorthand term for the early Greek epic poets, approximate contemporaries of Homer.  We know no more about these poets than we know about Homer, but modern scholars regard them as having composed orally, as did Homer.  In the classical period, surviving early epic poems were ascribed to these authors, just as the "Iliad" and "Odyssey" were ascribed to Homer.  Together with Homer, whose "Iliad" covers a mere 50 days of the war, they cover the complete war "cycle", thus the name.  Most modern scholars place Homer in the 8th century BC.  The other poets listed below seemed to have lived in the 7th–5th centuries BC.  Excluding Homer's, none of the works of the cyclic poets survive.

Epic Cycle: The Epic Cycle (Greek: Ἐπικός Κύκλος , "Epikos Kyklos") was a collection of Ancient Greek epic poems, composed in dactylic hexameter and related to the story of the Trojan War, including the "Cypria", the "Aethiopis", the so-called "Little Iliad", the "Iliupersis", the "Nostoi", and the "Telegony".  Scholars sometimes include the two Homeric epics, the "Iliad" and the "Odyssey", among the poems of the Epic Cycle, but the term is more often used to specify the non-Homeric poems as distinct from the Homeric ones.

Cypria: The Cypria (Greek: Κύπρια "Kúpria"; Latin: "Cypria") is an epic poem of ancient Greek literature, which has been attributed to Stasinus and was quite well known in classical antiquity and fixed in a received text, but which subsequently was lost to view.  It was part of the Epic Cycle, which told the entire history of the Trojan War in epic hexameter verse.  The story of the "Cypria" comes chronologically at the beginning of the Epic Cycle, and is followed by that of the "Iliad"; the composition of the two was apparently in the reverse order.  The poem comprised eleven books of verse in epic dactylic hexameters.

Messapus: Messapus, a character in Virgil's "Aeneid", appears in Books VII and IX of the Latin epic poem.  He was a famous tamer of horses and king of Etruria, known for being one "whom no one can fell by fire or steel" (Mandelbaum, VII.911-912); perhaps because he is a son of Neptune.  Although accustomed to peace, in Book VII Messapus joins forces with Turnus in his battle against Aeneas and the Trojans.  In Book IX, which recounts the nighttime raid by Nisus and Euryalus on the Rutulian camp, the battle helmet of Messapus is taken by Euryalus.  Light reflected off the stolen helmet, betraying Euryalus to his enemies and leading not only to his own death, but also that of Nisus.

Supporting paragraphs: Messapus Troy
Answer: Turnus