That fact should not be verified. Prussia emerged out of the Holy Roman Empire, but became Germany in 1871 at the end of the Franco-Prussian War due to the manipulation of Otto von Bismarck. This period was known as the second reich (empire). The reich ended at the end of World War I when Germany was defeated. The lands that it had gained in the past centuries were returned (see irridentism): Alsace-Lorraine went to France (lost 1871), Poland, which had been partitioned to nonexistence in 1795 was recreated, and German lands were added so that Poland would have Danzig (Gdansk) a valuable port. No lands went to Russia, but after the revolution, the Russians gradually retook lands that they had lost to Germany in 1917 at the treaty of Brest-Litovsk. Please check the source that verified this fact