An interesting citation from the 'battle of the gods' is Il 20.67
Always in Homer's version of the Troy story, Apollo and Poseidon find themselves on opposite sides. Scholars have wondered why this is the case. See e.g. Il 24.25-
Poseidon and Zeus are also in a somewhat ambivalent relation. Perhaps because Zeus was born the youngest of three brothers but (like his father Kronos) he became the leader of the gods (Il 13.355). Normally of course it is the eldest son who takes the inheritance. So, like Jacob in the bible, Zeus 'becomes first-born'(1). Poseidon accepts this but not wholeheartedly and there is clearly some tension left. See most clearly Il 15.157-219. There are a number of other features which are important:
All this forms the context in which Homer's picture of Poseidon is drawn. I find it likely that members of this family, as I suppose Homer was, would refer to their city as 'Pylos-on-the-beach' and that when they refer to the will of Poseidon, they refer to a long-standing family policy aimed at acquiring a strong power-base on the Asian mainland. In terms of the Homeric picture: Poseidon, like the Ionians, 'has the sea' but 'wants the land'. Zeus (or Fate) however says that he cannot have it. See Il 15.187-. The whole picture suggests strongly that Poseidon has Kronos-like ambitions: he wants to rule (again?(2)) on earth.
Let us translate the myth: to become king again (-> Hera) the Neleids (-> Poseidon) have devised a clever plan of war (-> Athena) to conquer themselves a power base in Asia (-> Troy). To lure the people into doing this for them, they tell the story of the abduction of Helen which turns out to be a free pass to go and grab girls in revenge (-> Aphrodite). Zeus did support this "emigration policy" (some say it was his plan)
Homer presents this rivalry between these gods in a fairly light-hearted way, but I think there may be a dangerous tension in the Greek world behind it:
Curiously, in this scene Zeus is portrayed as obeying Hera (οὐδ' ἀπίθησε πατὴρ ἀνδρῶν τε θεῶν τε, Il 4.68). see also: Il 8.198-212 (Hera wanting Poseidon to act but he is unwilling to face Zeus), Il 15.178- (Zeus threatening to fight him).
There is also a link with the 'golden rope' episode in Il 8.19: