Ducats were gold coins, and also units of account, formerly used in most European countries; including Holland, Russia, Austria, and Sweden. The value of a ducat was generally about 9s. 4d, that is nine shillings and fourpence.
There was also an Italian ducat silver coin , value about 3s. 6d.
According to The Oxford English Dictionary, the first Ducat was a silver coin issued in 1140 by Roger II of Sicily, as Duke of Apulia.
In 1284, the first gold ducat, also called a zecchino (from which we get the word sequin) d'oro, was struck at Venice under the doge John Dandolo. This coin, worth about 9s., bears on one side figures of St. Mark and the Doge, and on the other a figure of Christ with the legend 'Sit tibi Christe datus quem tu regis iste ducatus'; this, though it did not originate, may have contributed to spread the name, which was subsequently applied to the gold coins of various European countries.
Ducats were issued by Austria in 1612, and probably earlier. The last regular issue of ducats was in 1914. All the 4 ducats dated 1915 are restrikes, of which there were 496,501 struck between 1920 and 1936. Four ducat coins dated 1915 are still being produced by the Austrian Mint as official restrikes.
Franz Joseph I was born in 1848, and died in 1916.
There is some tradition in Austria for issuing commemorative coins posthumously. After the death of Francis I in 1765, his widow, Maria Theresa, decreed on the 21st July 1766, that coins would be issued bearing the portrait of Francis I, and the date of his death. Alphabetical mintmarks were to be used to denote the actual year of issue, with A = 1766. The posthumous coins were issued erratically.
Also after the death of Maria Theresia in 1780, the very famous Maria Theresa Thaler continued to be issued bearing her portrait and the date 1780.
The laureate head, facing right, of Emperor Franz Joseph I
FRANC IOS I D G AUSTRIAE IMPERATOR
The arms of Austria superimposed upon a crowned double-headed Imperial eagle.
HUNGAR BOHEM GAL LOD ILL REX A A 1915
Ducats were produced in high purity gold, 233/4 carats, making them among the highest purity gold coins ever issued for circulation.
Because they have inherited their design and appearance from medieval gold coins, they are very thin compared with modern coins, at just 0.7 mms. thick.