The arrival of a healthy male heir is an essential moment for any monarchy, but it's not always a guarantee. And for the Habsburgs it became a serious problem. 

The birth of Balthasar Charles was particularly welcomed by his parents. King Philip IV of Spain had married Elisabeth of France, the daughter of King Henry IV and Marie de Medici, in 1615. Elisabeth had been just thirteen years old at the time, while Philip was 16, so the pair were probably forbidden from sleeping together until they had grown up a bit. Their first child, a daughter named Maria Margaret, was born in 1621. Sadly she died two days later. 

In a previous post I looked at Don Carlos was almost a king of Spain. But attention should also be paid to his maternal uncle, Joao Manuel of Portugal. Like Carlos, Joao was a victim of the royal families’ penchant for inter-family marriages.

In the 17th century you couldn’t throw a stone without hitting a royal prince called “Louis”. As a result the figure in this blog post is going to be referred to by the name "Young Louis" or "Petite Dauphin", otherwise you’re going to get sick of the name while reading it and I’m going to get lost while I write it.

I’ve previously written about an English “Almost King”, Prince Arthur Victor, whose early death led to his younger brother claiming both his crown and his pretty bride. The Romanov dynasty of Russia went through a similar situation a few decades earlier, although in their case the prince concerned was far more promising.

Although many boys and young men from royal families have been felled by illness and bad luck there aren’t many who can be said to have been potentially murdered on their father’s orders.

Enter Don Carlos, Prince of Asturias.

When he became Holy Roman Emperor in July 1658, Leopold I was already very familiar with how essential a spare to the heir was. 

Born in August 1198, Alexander II became King of Scotland at the age of 16. Two years later he attempted to take advantage of the chaos caused in England by the revolt against King John, but after John's death led to a change in English leadership the Scots were forced to return home. The Treaty of Kingston was signed in 1217, and in the following years diplomatic efforts led to the still unmarried Alexander being given the hand of the young English princess Joan.

King Manuel I of Portugal is known as “Manuel the Fortunate” because he wasn't supposed to become King. He was the youngest of his parents nine children and the last of their six sons, but illness and murder conspired to leave him as the sole heir to both his parents lands and the family's claim to the Portuguese throne.

King James V came into his inheritance at the tender age of 18 months, after his father died at the Battle of Flodden. His youth was spent with various Scottish Lords, including his stepfather, fighting out for custody and control of the young King. At the age of sixteen he managed to escape his stepfather and declared his minority over, although he still struggled against competing factions at his court.

This month's “Desperately Seeking Sons” candidate is King Baldwin I of Jerusalem.

Only the second King of Jerusalem, Baldwin was married three times during his life, and even courted controversy with his third marriage as his second wife was very much alive and very cross with how she had been treated. Historians have debated Baldwin's treatment of the women in his life, with some suggesting that he was homosexual (which may also explain why he doesn't appear to have fathered any children, legitimate or otherwise). But with so little information about his wives and their marriages, making a guess at his sexuality is difficult.