Over the years Denmark lost many of the lands that it controlled in battle. Denmark's biggest war defeat was the "Second Schleswig War" (in 1864) when the duchies of Schleswig and Holstein was conquered by the Kingdom Prussia (now a part of Germany). This was a big loss for Denmark and, consequently, it began a policy of neutrality after the loss, meaning it would no longer take part in any wars or support other countries. Denmark did not take part in the First World War.