In which decade did nuclear submarines start to replace diesel submarines?

Nuclear submarines began to replace diesel submarines in the 1950s, marking a significant advancement in naval technology. The first operational nuclear submarine, the USS Nautilus, was launched in 1954, showcasing the advantages of nuclear propulsion, such as longer underwater endurance and the ability to operate at higher speeds compared to diesel-electric submarines. This transition was driven by the need for enhanced stealth and sustained operational capabilities during the Cold War, making the 1950s a pivotal decade for submarine warfare.

In contrast, earlier years, such as the 1940s, saw the predominance of diesel submarines, as nuclear technology was in its infancy and not yet applicable to submarine design. While the 1960s continued to see advancements in nuclear submarine technology, the foundational shift had already begun in the previous decade. The 1970s did further develop nuclear submarine capabilities, but the initial replacement trend had clearly started in the 1950s.