I think the answer by mmcc is mostly correct. They are probably parts of an old electrical device battery. But the round case is not steel. Steel (ferrous metals) rust (oxidize) like the narrow strap with a rusty brown color. Non-ferrous metals oxidize in different ways. The green inside is a typical oxidation color of copper.
The canister is some type of non-ferrous alloy, I have some guesses at what it might be, but they are just guesses. If there are (or were) 6 canisters connected together it would be for a 12 volt battery. Though 6 volt was more popular around 1944.
I Googled around for a battery museum that might have images of popular batteries from 1944, but those searches did not go well, leading mostly to artillery battery.
I am guessing that someone is going to come along and be able to say, what kind of battery it was and what specific use it served, but it might be a while. I look forward to reading their answer.