His seagoing career included being sunk twice in the space of one month, and being charged and convicted of piracy by the Vichy French, after which he was imprisoned in Timbuktu.

All of the crew survived and escaped in two boats; de Neumann's lifeboat was picked up by the American freighter SS Exhibitor.

HMS Cilicia arrived at Freetown on 17 June 1941, and de Neumann volunteered as Second Officer aboard the Royal Navy prize vessel SS Criton (captured from the Vichy French).

Criton's crew were escorted under armed guard to Conakry, where the executive officers were tried and found guilty of piracy by a Vichy French naval court-martial and imprisoned in Timbuktu.

De Neumann was eventually released at the end of December 1942, and arrived back in the UK aboard the armed merchant cruiser HMS Asturias in mid-January 1943.

In 1953, de Neumann resigned his command of HMRC Vigilant following the Spithead Review and transferred to the Port of London Authority.

[8] De Neumann was commended for his handling of the rescue attempt following the sinking of the Tug Sunfish under Tower Bridge on 12 March 1960.

[9] Three items which de Neumann brought home from Timbuktu were on loan to the Imperial War Museum in London and displayed in the Survival at Sea Exhibition.