“Two hundred years ago this month, at the end of the Napoleonic Wars, Britain acquired the tiny island of Heligoland in the North Sea. Ashley Cooper and Stephen Cooper describe how, as the European rivalries shifted in the 19th century, it came to be used as a bargaining chip with Germany.”
By Stephen Cooper in History Today, volume 64, Issue 1, 2014 (article partly available online, subscription needed for full article).