[UncleSlacky]

The oil wells were in Pennsylvania, which was on the Union side.

[sirobg]

So the whales are saying: "May They Never Secede" talking about the wells, in reference to the confederacy whom already seceded. And they say this because obviously if the wells "seceded", humans would go back to whale hunting.

Do I understand it correctly now?

[fzzzy]

Yes.