Apollonia, known in the Early Islamic period as Arsuf and in the Crusader Kingdom of Jerusalem as Arsur, was an ancient city on the Mediterranean coast of today's Israel. In Israeli archaeology it is known as Tel Arshaf. Founded by the Phoenicians during the Persian period in the late sixth century BCE, it was inhabited continuously until the Crusader period, through the Hellenistic, Roman, and Byzantine periods, during the latter being renamed to Sozusa. It was situated on a sandy area ending towards the sea with a cliff, about 34 kilometres (21 mi) south of Caesarea.

The Third Crusade (1189–1192) was an attempt led by three European monarchs of Western Christianity to reconquer the Holy Land following the capture of Jerusalem by the Ayyubid sultan Saladin in 1187. For this reason, the Third Crusade is also known as the Kings' Crusade.