On Wednesday I got not only a postcard but also a cover from Bulgaria.
200th birthday of Ivan Aivazovsky (issued 26-07-2017)
Inside was a Bulgarian souvenir sheet about the Centenary of the Battle of Doiran (issued 09-05-2017).
Bulgaria entered World War I on 14th October 1915 alongside the Central Powers. With the entry into World War I Bulgaria hoped to reclaim territories lost during the Balkan Wars. Although it was the smallest member of the Central Powers in area and in population, Bulgaria made vital contributions to their common war effort. After Bulgaria's entry the Balkan theatre saw successful campaigns of rapid movement in 1915 and 1916, but soon the conflict degraded into a state of trench warfare and Bulgaria was forced to seek peace in 1918. An armistice with the Entente was signed on 30th September 1918.
The Second Battle of Doiran was fought between Bulgaria and the United Kingdom in April and May 1917. The battle ended with a Bulgarian victory and thus thwarted an Allied breakthrough at the Balkan front.
Thank You very much Ganka!