German attempts to keep France isolated by maintaining alliances with the other powers of Europe began to unravel in the late 1880s when Russia broke with the League of Three Emperors over conflicting interests with Austria-Hungary. In 1894, the Russians went a step further and joined in a formal alliance with the French. There were now two opposing power blocs in Europe.
In late 1885, the nationalistic Bulgarian Secret Central Revolutionary Committee (BSCRC) led a series of uprisings in Eastern Rumelia in favor of union with the northern Principality of Bulgaria. The revolt culminated on 18 September [6 September O.S.] 1885, when the rebels took over the Eastern Rumelian government in Plovdiv and proclaimed Bulgarian unification. The Principality of Bulgaria obliged four days later, annexing Eastern Rumelia as South Bulgaria.in wikipedia
The unification of Bulgaria was not recognized by the Great Powers and strongly opposed by Serbia, who saw the large new state as a threat. Under the promise of protection by Austria-Hungary, Serbia attacked Bulgaria but was defeated in just two weeks, leading the Great Powers to recognize Bulgarian unification.in wikipedia
By 1887, the decline of Ottoman power in the Balkans had made Russia and Austria-Hungary into rivals, while the rising militarization of Germany directly threatened Russia. This disincentivized Russia from renewing the League of the Three Emperors, causing the alliance to end.in wikipedia
On 23 November 1890, King William III of the Netherlands died. Rule over the Netherlands passed to his only child, Queen Wilhelmina, who was barred by semi-Salic law from also serving as Grand Duchess of Luxembourg. Therefore, the Luxembourgish throne passed to William’s father-in-law Adolphe, the former Duke of Nassau.in wikipedia