 Complete the following phrase:  Preussischer Adler was an iron-hulled paddle steamer originally built for the Prussian postal service to operate on the packet route between Prussia and Russia in the mid-1840s. At the time, the Prussian Navy was an anemic force consisting of a handful of small sailing vessels and cannon-armed yawls. The ship was requisitioned early in her career during the First Schleswig War to defend the Prussian coast from the more powerful Danish Navy that imposed a blockade on Prussias and the other German states ports. She took part in a short battle with the Danish brig , the first engagement involving the Prussian fleet. She returned to commercial duties after the war and served in that capacity uneventfully until 1862, when the expansion of the Prussian Eastern Railway rendered her superfluous. Purchased by the Prussian Navy, she was in the Mediterranean Sea with a pair of gunboats on the eve of the Second Schleswig War. The ships were recalled to Prussia but arrived after the outbreak of war. They joined a pair of Austrian screw frigates to attack the Danish blockade squadron in the 