Complex sentence: In the time of outbreak of the short April War in 1941, Sergej Mašera was a lieutenant on "Destroyer Zagreb" stationed in Dobrota (Bay of Kotor), the first officer in charge of the ship's artillery.
Split into simpler sentences: In the time of outbreak of the short April War in 1941, Sergej Mašera was a lieutenant on "Destroyer Zagreb" stationed in Dobrota on the (Bay of Kotor). He was the first officer in charge of the ship's artillery.