[3] In late December 1940, she sailed for Cherbourg where her gun platforms were strengthened and additional fresh water tanks were added.

[3] Around 10 January 1941, Esso Hamburg left Cherbourg for the North Atlantic, taking a position south of Cape Farewell in Greenland.

[3] Esso Hamburg was part of Operation Berlin, which sailed on 22 January 1941, along with the naval oilers Uckermark and Ermland plus the tankers Schlettstadt, Adria and Friedrich Breme.

[3][5] According to later prisoner statements, the ship remained in the area north of the Grand Banks of Newfoundland for over two months, where the cold was considered intense (as the crew lacked warm clothing).

[3] These prisoners stated that American patrol vessels capable of 20 knots were sighted and Esso Hamburg was fired on, leading Captain Braunwarth to think his ship was being followed.

[3] According to Captain Braunwarth (whose interrogation statements have been proven to be false or unreliable), he decided to return to port in St. Nazaire after the rudder was damaged in a storm.

After the two days passed and having received no orders, the ship sailed south between the 30th and 32nd meridian to what the captain stated was a safer area.