1899 the 30th of September Percy Pilcher unveils his triplane and become the first man in history. The British army sees the benefit of the aeroplane for scouting and triplanes are deployed as scouts in both the Boxer Rebellion and the Second Boer War. Much like in OTL the aircraft was seen as unimportant by most armed forces.
The United States however was a enthusiastic user of the aeroplane and in the 1912 race war the USA became the first nation to bombs specific designed to be airdropped in the defence of the US territory of Cuba.
In 1914 a Austrian prince is killed by Serbians terrorists when bomb blows up his car. Austria-Hungary invades Serbian and the web of European alliances draw Europe into the Great War. 11 days after the sinking of the Lusitania on May the 18th of 1915 the United States of America declared war on Germany, Woodrow Wilson famously vowing “America is too proud not to fight”. Soon afterwards the Ottoman empire pulled out of the war leaving Germany and Austria-Hungary isolated. During the Battle of the Somme, British Allen Tanks were first used. Along with American semi automatic rifles and bombing runs the result is a decisive Allied victory and a turning point in the war.
By June the 6th 1917 the Central Powers surrendered. With this the Allies attention turned to Russia and crushing the Bolshevik Red Army. In 1919, Bolsheviks forces were all but destroyed. Russia became a constitutional democracy. In the east Japan set up the puppet state of Japanese Russia.
To rebuild Europe and pay off the massive debt created by the wars and ensure a lasting peace the European Alliance was set up, which functions much as the OTL European Union does. By 1929 they world was flourishing, the Ludwig Dürr’s “European Maidens” the LZ 127 Germania, LZ 128 Helvetia and LZ 129 Britannia attend a ceremony in Cuba to mark the island becoming the 51st state of the USA.