THOMAS;

In September of 1955, the Soviets were the first country in the world to launch a balistic missile from a submarine. Source:

[en.wikipedia.org]

As for launching rockets from a submarine, in May/June of 1942, the U-511 launched 21 to 30cm Army rockets from a standard issue "Wurfgerat" launcher. These were not ballistic missiles.

The Germans developed a plan to send three 500-ton containers towed by a single snorkel-equipped submarine, each container,
trimmed to neutral buoyancy, concealed a V-2. Upon reaching the start location, the containers would be trimmed to a vertical position, and the rockets launched. The idea was filed away until 1944, when it was given the code name "Prufstand XII" and Vulkanwerft secretly began work on three containers. While the records indicate that at least one ssuch submarine launch container was completed, it was never tested with a live firing. The concept was proven sound by the Soviets in the 1950s. Using captured plans and German engineering assistance, they produced the "Golem" submarine towed missile launcher. American engineers took the next step with the "Regulus" and "Polaris" programs, placing the missile and launcher into the submarine.

Hope this helps,

ROBERT M.