Galler was born into a Baltic German family of a military engineer Philipp Michael Hugo von Haller (Galler) and joined the Baltic Fleet on completing the Naval school in 1905. During World War I he was squadron gunnery officer of the Battleship Division, executive officer of the "Slava" and commanded the destroyer "Turkmenets Stavropolski". After the October Revolution he joined the Bolsheviks and participated in the Ice Cruise of the Baltic Fleet. Subsequently, he commanded the destroyer "Mecheslav", the battleship "Andrei Pervozvanny" and was subsequently chief of staff of the Baltic Fleet during the British Campaign in the Baltic 1918–1919.