Scandinavism was at its height during this period and contributed to increasing rapprochement between the Union partners. It supported the idea of Scandinavia as a unified region or a single nation, based on the common linguistic, political, and cultural heritage of the Scandinavian countries. (These three countries are referred to as "three brothers" in the sixth stanza of the national anthem of Norway.) This elite movement was initiated by Danish and Swedish university students in the 1840s. In the beginning, the political establishments in the two countries were suspicious of the movement. However, when Oscar I became king of Sweden and Norway in 1844, the relationship with Denmark improved and the movement started to gain support. Norwegian students joined in 1845 and participated in annual meetings alternating between the countries. During the war between Denmark and Prussia in 1848, King Oscar offered support in the form of a Norwegian-Swedish expeditionary force, though the force never saw combat. The movement received a blow from which it never fully recovered after the second Danish-German war over Schleswig in 1864, when the Swedish and Norwegian governments jointly forced King Charles XV to retract the promise of military support that he had given to the king of Denmark without consulting his cabinets.