 Complete the following phrase:  From 1848 to 1864, Denmark and the German Confederation fought over control of the two duchies of Schleswig and Holstein. Historically, the duchies had been ruled by Denmark since medieval times, but there remained a large German majority. This majority was sparked to rebellion after Frederick VII of Denmark announced on 27 March 1848 the duchies would become an integral part of Denmark under his new liberal constitution. Prussia soon became involved, supporting the uprising and beginning the 