The european alliances shown on this map were made in an attempt to?

In 1871 two new major states of Europe had been formed—the German Empire and the kingdom of Italy. The new German Empire, under the hand of Otto von Bismarck, was steered carefully, always with an eye upon France, for the Franco-Prussian War (1870–71) had left France thirsting for revenge and for recovery of the lost provinces of Alsace and Lorraine.
Germany had allied itself with Russia and Austria-Hungary in the Three Emperors' League, but Austria-Hungary and Russia were not the best of friends, partly because they were at odds over the Balkans and partly because Russia represented the Pan-Slavic movement, whose program threatened the very existence of Austria-Hungary. The Treaty of San Stefano (1878), following the Russo-Turkish War, furthered the cause of Pan-Slavism through the creation of a large Bulgarian state and offended Austria-Hungary as well as Great Britain. A European conference (1878; see Berlin, Congress of), called to revise the treaty, caused a sharp decline in the friendship between Russia on the one hand and Austria-Hungary and Germany on the other; Bismarck formed (1879) a secret defensive alliance—the Dual Alliance—with Austria-Hungary.

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.