I take it it's primarily the bits of dialect you're hanging up on? I'm American myself, but I've been reading verse by people like Hardy, Kipling, and Lawrence since my teens, so I'll essay it: What Hardy is doing is taking rural pronunciations of common English phrases (sometimes grammatically archaic by the standards of the Queen's English) and saying how similar they are to German phrases with the same meaning. Thus

thu bist = "thou beest": du bist
er war = "he were": er war
ich woll = "I will": ich will
er sholl = "he shall": er soll

And from this, he's drawing the point that the English and the Germans are of common descent and common linguistic heritage and it's a damned shame for them to be killing each other.