Milan Spasić was a naval Lieutenant of the Royal Yugoslav Navy. During the April War, Spasić, along with his fellow Lieutenant Sergej Mašera, scuttled the destroyer Zagreb in the Bay of Kotor near Tivat to prevent it from falling into the hands of the Italian Royal Navy. Both Spasić and Mašera died in the scuttling.

The Royal Navy, commonly the Royal Yugoslav Navy, was the naval warfare service branch of the Kingdom of Yugoslavia. It was brought into existence in 1921, and initially consisted of a few former Austro-Hungarian Navy vessels surrendered at the conclusion of World War I and transferred to the new nation state under the terms of the Treaty of Saint-Germain-en-Laye. The only modern sea-going warships transferred to the new state were twelve steam-powered torpedo boats, although it did receive four capable river monitors for use on the Danube and other large rivers. Significant new acquisitions began in 1926 with a former German light cruiser, followed by the commissioning of two motor torpedo boats (MTBs) and a small submarine flotilla over the next few years. When the name of the state was changed to Yugoslavia in 1929, the name of its navy was changed to reflect this. In the late 1920s, several of the original vessels were discarded.