The Kingdom (Or Tsardom) of Bulgaria was a constitutional monarchy created in 1908 as Ferdinand I elevated the Bulgarian state from principality to kingdom. The state was almost constantly at war throughout its existence, lending to its nickname as "the Balkan Prussia". For several years Bulgaria mobilized an army of more than 1 million people from its population of about 5 million and in the next decade (1910–20) it engaged in three wars - the First, the Second Balkan War and the First World War. After this the Bulgarian army was disbanded and forbidden to exist by the winning side of the World War and all plans for national unification of the Bulgarian lands failed. After less than two decades Bulgaria was again warring for national unification in the Second World War and was fighting again on the losing side (until it switched to the Allies in 1944), which was a third lost war. In 1946, the monarchy was abolished, its final Tsar was sent into exile and the Kingdom was replaced by a People's Republic.
Ferdinand I ruled Bulgaria between 1887 to 1918 through three wars, until abdicating after the Central Powers lost. He proclaimed the Bulgarian de jure independence from the Ottoman Empire and waged two wars against it (The Balkan Wars), and although Bulgaria suffered great losses in these conflicts he would still eventually enter World War One in the Central Powers' side, to reclaim territories lost during the Second Balkan War - This expansionism would be his downfall.
A Quick-firing gun has several characteristics which taken together mean the weapon can fire at a fast rate. The quick-firing howitzer offered the potential for practical indirect fire. Traditional howitzers had been employed to engage targets outside their line of fire, but were very slow to aim and reload. Quick-firing weapons were capable of a heavy indirect bombardment, and this was the main mode of their employment during the 20th century.
Despite the highly agrarian nature of Bulgaria during this period their educational system was highly successful, with less than half the population being illiterate. Education reached more of the lower classes than anywhere else in Eastern Europe at this time.