Poseidon was very popular in Eleusis and was on a first-name basis with the royal family. He received cult worship there, with processions dedicated to him in harvest festivals. There were also numerous temples and sanctuaries where he was honoured alongside other Eleusinian deities. He was also the lover of Demeter, whose mystery cult in Eleusis was ranked second only to Delphi in religious importance in the Greek world. Many legendary Eleusinian kings and heroes were his sons or relatives and he served as the town’s divine father. So when all else failed, he called upon his son (and king) Eumolpus to avenge him by invading Athens.