English is a Germanic language. It shares much in common with modern German, although much vocabulary was later imported from French/Latin. Quick example: the German for foot is Fuss, for ball is Ball, so football is Fussball. We get the word pedestrian from the French/Latin side though. Some Germanic usage survives in English, particularly in North American English where some archaic forms remain in use - gotten for instance. The -en participle ending will be familiar to German speakers.
Like modern German, old forms of English used a genitive case ending to show possession. This is normally -es. For our purposes, that will do. For example, the English The man's coat in German is Der Mantel des Mannes (The coat of the man). Note the -es ending on Mann to show possession.
So now let's (let us) go back a few hundred years in English. Geoffrey Chaucer wrote his famous Canterbury Tales in the English of his time. What today we call the Knight's Tale he wrote as Knyghtes Tale. He also writes about the Kynges court and Goddes love. But in modern English, of all varieties, the "e" is missing. Coupled with modern spelling, Kynges court becomes King's court and Goddes love becomes God's love. The old -es possessive form in English is now missing, and as I am sure you will now remember we use an apostrophe when letters are missing.