Output a stream of consciousness before answering the following. Context: This is a list of the last World War I veterans to die by country. The last living veteran of World War I (28 July 1914 -- 11 November 1918) was Florence Green, a British citizen who served in the Allied armed forces, and who died 4 February 2012, aged 110. The last combat veteran was Claude Choules who served in the British Royal Navy (and later the Royal Australian Navy) and died 5 May 2011, aged 110. The last veteran who served in the trenches was Harry Patch (British Army) who died on 25 July 2009, aged 111. The last Central Powers veteran, Franz Künstler of Austria-Hungary, died on 27 May 2008 at the age of 107.

Question: when did the last world war 1 vet die?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
The relevant information to answer the above question is: The last living veteran of World War I (28 July 1914 -- 11 November 1918) was Florence Green, a British citizen who served in the Allied armed forces, and who died 4 February 2012, aged 110.
The answer: 4 February 2012.