<a href="https://en.wikipedia.org/wiki/William_I_of_the_Netherlands" id="mwUg" rel="mw:WikiLink" title="William I of the Netherlands">Prince Willem</a> proclaims himself King of the <a href="https://en.wikipedia.org/wiki/United_Kingdom_of_the_Netherlands" id="mwUw" rel="mw:WikiLink" title="United Kingdom of the Netherlands">United Kingdom of the Netherlands</a>, the first <a href="https://en.wikipedia.org/wiki/Constitutional_monarchy" id="mwVA" rel="mw:WikiLink" title="Constitutional monarchy">constitutional monarch</a> in the Netherlands.