The new issue "Centenary of World War I" by Gibraltar post is comprised of 6 stamps, a set of 6 sheetlets, a First Day Cover, a Presentation Pack and a Limited Edition (250 copies) Imperforate proof enclosing a Certificate of Authenticity produced by BDT International Security printers.
World War I was a global war centered in Europe that began on 28 July 1914 and lasted until 11 November 1918. More than 9 million combatants were killed. The war drew in all the world's economic great powers, which were assembled in two opposing alliances: the Allies (based on the Triple Entente of the United Kingdom, France and the Russian Empire) and the Central Powers of Germany and Austria-Hungary.
Although Italy had also been a member of the Triple Alliance alongside Germany and Austria-Hungary, it did not join the Central Powers, as Austria-Hungary had taken the offensive against the terms of the alliance. These alliances were both reorganized and expanded as more nations entered the war: Italy, Japan and the United States joined the Allies, and the Ottoman Empire and Bulgaria the Central Powers. Ultimately, more than 70 million military personnel, including 60 million Europeans, were mobilized in one of the largest wars in history.
Although a resurgence of imperialism was an underlying cause, the immediate trigger for war was the 28 June 1914 assassination of Archduke Franz Ferdinand of Austria, heir to the throne of Austria-Hungary, by Yugoslav nationalist Gavrilo Princip in Sarajevo. This set off a diplomatic crisis when Austria-Hungary delivered an ultimatum to the Kingdom of Serbia, and international alliances formed over the previous decades were invoked. Within weeks, the major powers were at war and the conflict soon spread around the world.