How were King George V of England and Tsar Nicholas II of Russia related?

These two men were first cousins. King George V of England's mother was Alexandra of Denmark and Tsar Nicholas II's mother was Dagmar of Denmark. Alexandra and Dagmar were sisters explaining the similarity in physical appearance of their sons.

The picture was taken in Berlin at the royal wedding of Germany's Kaiser Wilhelm II's daughter, Princess Victoria Louise of Prussia on May 24, 1913. Wilhelm was also related to the two men. Wilhelm and George were first cousins while Wilhelm and Nicholas were third cousins.

In a diplomatic gesture, Wilhelm invited almost his entire extended family to the wedding. It became the largest gathering of reigning monarchs in Germany since German unification in 1871 and one of the last great social events of European royalty before WWI began 14 months later.

Both men are in German military uniforms at the wedding as it was quite common for European royalty to promote each other into each other's militaries. As an example, Nicholas is in the uniform of the Westphalian Hussars and George is in the uniform of the Rhenish Cuirassiers - their respective German regiments.

George V (1865-1936) was King of the United Kingdom, the British Dominions and Emperor of India from 1910 until his death. Tsar Nicholas II of Russia (1868-1918) was the last Emperor of Russia ruling from 1894 until his forced abdication in 1917. One year later he was executed along with members of his family.