@johnjohn I can't tell you about the stamp but I can tell you about who's on it.
Field Marshal Radetzky was an Austrian general from 1785 alllll the way until his death in 1858. He gave his life to the army and his country and was greatly honoured for it within his lifetime.
His record during the Napoleonic wars isn't terrific, he performed well where he was but was never fully utilized outside of a few specific points. All considered he's still #2 or #3 Austrian commanders from the wars behind Archduke Charles and behind/a little ahead of Count Johann I.
He's more famous however for what happened much after Napoleon was defeated at Waterloo however. In 1848 liberal revolts happened across most of Europe, and in Austria they were especially violent... A mob in Vienna forced the Emperor to abdicate, the Hungarians revolted in budapest and nearly marched on the capital before a combined Austrian-Russian army pushed them back, and in Italy by his lonesome was Radetzky with a small portion of the army to hold Veneto and Milan.
Radetzky at the start of the revolt was in Milan with his army of about 13,000. 'The Five Days of Milan' ended with Radetzky escaping from the city's riot and retreating to a series of fortresses where he managed to restore Austrian rule over Austrian Italy, and here he fended off the first attempt by Sardinia-Piedmont at annexing swaths of Austrian Italy. After this he marched to the aid of Pope Pius IX who the Italian liberals forced to flee Rome. After this a very famous song was composed by Johann Strauss for him called the Radetzky March. A decade after his death austria had been kicked out of Italy, diplomatically isolated from it's former ally of Russia, and would be beginning a road to recovery as the dual monarchy of Austria-Hungary.
I quite adore Radetzky, so it's nice to see Austria made a stamp of him.