She had been laid down in February 1914 as U-10 the fourth boat of the U-7 class for the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K.

After the outbreak of World War I in August 1914, the Austro-Hungarian Navy became convinced that none of the submarines of the class could be delivered to the Adriatic via Gibraltar.

British records say that U-69 was sunk by destroyer HMS Patriot on 12 July, but a German postwar study cast doubt on this.

The Austrian specifications called for two shafts with twin diesel engines (2,300 metric horsepower (2,269 bhp; 1,692 kW) total) for surface running at up to 17 knots (31 km/h; 20 mph), and twin electric motors (1,240 PS (1,223 shp; 912 kW) total) for a maximum of 11 knots (20 km/h; 13 mph) when submerged.

[8] U-69 successfully completed five war patrols in which she sank 31 ships with a combined a total of 102,875 gross register tons (GRT).

[10] Avenger had been patrolling off the Shetland Islands and was returning to Scapa Flow, when she was struck by a single torpedo on the port side.

Despite strenuous efforts to save her, Avenger foundered ten hours after being hit when her internal bulkheads collapsed.

According to author Dwight Messimer, two British sources report that HMS Patriot sank U-69 at position 60°25′N 1°32′E / 60.417°N 1.533°E / 60.417; 1.533 on 12 July.

The U-boat submerged and Patriot hunted the submarine until noon, when it loosed two depth charges that brought thick brown oil to the surface.