Neither technology by itself was new. The USS Nautilus (SSN-571) – the world's first nuclear-powered submarine – entered service in 1954, while the USS Albacore (AGSS-569) was the first to ...
Of course, nuclear power appeared in U.S. subs long before that, going back as far as 1954, with the introduction of the USS Nautilus (SSN-571), but it took some time for the older subs to age out ...