Captain Christian August Max Ahlmann Valentiner (15 December 1883 – 19 July 1949) was a German U-boat commander during World War I.

He was also listed as a war criminal by the Allies, for killing hundreds of civilians by sinking the passenger liner Persia without warning on 30 December 1915, contrary to international law.

[1] On 15 August 1902 he saved a ship's boy from drowning in Swinemünde's harbor, and received his first of many decorations, the Rettungsmedaille (life-saving medal).

On 14 May 1903 he saved an able seaman in Heligoland harbour from the waves and certain death, and was awarded the Order of the Crown Medal for his courage and valour in action.

In this job, on 17 January 1911, he saved all 30 men of U-3 by getting them out via a torpedo tube after it sank in Kiel Harbour due to an unclosed valve in the ventilation shaft.

On board he showed incredible skill and boldness and on training manoeuvres he sank several ships with drill torpedoes without ever being sighted.

His orders were to sink Russian warships in the Baltic Sea, but he failed, and blamed the old U-boat which did not have the capabilities of the newer boats in the Kaiserliche Marine.

After March, U-38 started to patrol in the eastern Mediterranean Sea and on 30 December 1915, U-38 and Valentiner sank the British passenger ship Persia without any warning.

The action took place under Germany’s policy of unrestricted submarine warfare, but broke the Imperial German Navy’s own restriction on attacking passenger liners, the Arabic pledge.

Valentiner was accused of "cruel and inhuman treatment of crews" in fifteen different incidents involving French, British, and Italian ships.

Valentiner then traveled to East Prussia and lived at Kadinen, an estate that his father managed, where he waited for the extraditions to proceed.

On 19 June 1949 Valentiner died in Sønderborg hospital from lung disease, likely precipitated by the inhalation of toxic vapors from the engines in his first U-boats, U-10 and U-3.