How did troy find out the greek attacked with the Trojan horse?

Troy discovered the Greeks had attacked with the Trojan Horse when a Trojan named Sinon's deception revealed the ruse. He convinced the Trojans that the wooden horse was a sacrificial gift, left to ensure the Greeks' safe return home. After bringing the horse into the city, the Greeks hidden inside emerged at night, opening the gates for their waiting army. This led to the downfall of Troy as the Greeks launched a surprise attack from within.