The welcome decision to end male primogeniture for the monarchy has presented historians like myself with an excuse to step outside the realm of history and speculate on what could have been. The current rule on primogeniture saw Prince Albert Edward become Edward VII in 1901 despite having an older sibling - a sister called Princess Victoria. Keeping up with the tradition of the age, Victoria, like her mother and grandfather, had married into German royalty. Germany at the time did not exist as a sovereign political entity though she was moving in that direction. Princess Victoria's husband was Prince Frederick of Prussia, nephew to the childless King Frederick Willian IV of Prussia, the most powerful of the myriad of German royal families.
So what could have happened if Princess Victoria, as the eldest child, inherited the throne on the death of her mother Queen Victoria in 1901 had the new rules on primogeniture been in place then? Firstly, Victoria II would have reigned for only a few months. She died in August 1901. Her son, by then the German Kaiser Wilhelm II, would have inherited the British Crown, and for good measure, would have become Emperor of India as well. Could we have ended up with a common monarchy for the British and German Empires? Could the history of the world have been different because or promogeniture?
Well, there has to be an assumption that the rulers of Britain in 1857, the year Victoria and Frederick were married, would have been prepared to accept the future union of the British and Prussian crowns. This was not without precedent. The Norman kings for example, had ruled England and realms on the Continent. The crown of the UK and Hanover had been united from 1714 until 1837. As Hanover operated Salic Law the crown went to the next male heir. Therefore in 1837 Ernest Augustus, the younger brother of Queen Victoria's father, rather than Victoria herself, inherited the Hanoverian throne. Ironically, the Prussians invaded Hanover in 1866 and annexed the kingdom, ending the separate Hanoverian monarchy.
It is one thing to have a joint crown with a minor state on the Continent. It is quite another for Britain to have the same head of state as a continental great power. Furthermore, the constitutional positions of the monarchy in the UK and Prussia were radically different. Balancing the two would have been at best very difficult. A study of the history of Britain from 1815 to 1914 shows that Britain steered clear of significant continental entanglements. I find it difficult to accept that the rulers of Britain in 1857 would have permitted a dynastic marriage that could have resulted in an entangling commitment.
But let's suppose they were prepared to accept the risk and allowed the marriage of Victoria and Frederick to go ahead. In August 1901, Kaiser Wilhelm would have become William V of Britain. This was a period in which Germany was emerging as the most powerful nation on the Continent yet the development of her navy was too early at this point to push her onto a collision course with Britain. Indeed, some such as Joseph Chamberlain in the 1890s were interested in pursuing friendship, even an alliance, with Germany.
So, could the union of the British and German crowns have led to Britain joining a different continental alliance? It is not too far fetched to believe that. After all, France and Russia were still regarded as traditional foes and France and Britain came close to blows over Fashoda in 1898. Britain and Germany had few colonial differences to cause them trouble. That was not the case with France. And Russia continued to be regarded as a threat to India.
Would this have meant no First World War? Possibly. But there again, imagine the impact of Britain and Germany coming closer together on France and Russia. They could end up feeling more threatened. Far from keeping peace on the Continent, arguably an alliance of Britain and Germany could have brought forward the date of a major war. It could have increased the Russian threat to India and it could have resulted in Britain and France coming to blows over colonial differences. Instead of the First World War starting in the Balkans, it could have started in North Africa.
This is, of course, speculation. It's not history. But it makes for some interesting alternative history theories.