The strange life and unhappy marriage of the 'first' Princess Charlotte

Modern royal fans hear the name 'Princess Charlotte' and picture the bubbly daughter of Prince William and Kate Middleton, who turns six this weekend.

But almost 120 years before that Charlotte was born, another royal shared her name.

Born to Louis II, Prince of Monaco, in 1898, this Charlotte was a Hereditary Princess of Monaco, though she experienced a very different life to her modern counterpart.

Most tragic was her unhappy marriage to a man who could never love her, a scandal that rocked the Monegasque royal family.

The 'first' Princess Charlotte

Born at the turn of the 19^th century, Charlotte was the illegitimate daughter of a cabaret singer and Louis, Prince of Monaco.

Her father was heir to the Monegasque throne, making her birth a difficult situation for the royal family, as illegitimate children were largely ignored.

But Louis had no siblings and no legitimate children, meaning the monarchy had a very real succession crisis on its hands.

Not wanting the Monegasque throne to fall into the hands of some other European relatives with claims to the crown, the royal family decided to recognise Charlotte.

A law was passed on May 15, 1911, when she was 13 years old, that recognised her as Louis' daughter and made her an official member of the royal family.

It was a controversial decision and required Louis to officially adopt Charlotte in 1919, when she was 21, to ensure her place in the line of succession.

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As such, when her grandfather Prince Albert I of Monaco died in 1922 and Louis inherited his crown, Princess Charlotte became heir presumptive of Monaco.

Securing the royal line

Not wanting to face the possibility of a second succession crisis, Prince Louis was eager to have his daughter married before he took the throne.

He arranged for her to wed a French nobleman, Count Pierre Marie Xavier Raphaël Antoine Melchior de Polignac.

Pierre was close in age to Charlotte and fond of the arts, making him a seemingly promising match for the young princess.

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Educated and high-born, Pierre should have been a model husband; indeed, there were no signs he'd be anything but that when he and Charlotte wed in March 1920.

He became a Prince of the Monegasque royal family and within three years he and Charlotte had welcomed two children, Princess Antoinette Louise Alberte Suzanne in December 1920 and Prince Ranier III in May 1923.

The royal line was secure, but there was a terrible complication in Charlotte and Pierre's marriage.

A doomed marriage

Though Charlotte and Pierre seemed an ideal match and had gone along with the marriage, even having children, there was one huge issue; Pierre was gay.

Their marriage had been arranged for them, meaning it's unlikely his sexuality was revealed until after he and Charlotte wed.

At the time, homosexuality was still incredibly taboo, and it's understood Pierre wanted to keep his sexuality a secret.

For her part, Charlotte was no model wife. She reportedly engaged in several affairs, even moving in with one of her lovers after separating from Pierre.

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The couple quietly split in the mid-1920s after the births of their children but didn't officially divorce until 1933.

It's believed Prince Louis knew the true reason the marriage failed.

At the time, a magazine reported: "The union ended ... under circumstances which prompted the temperamental father-in-law to vow he would call out the Monégasque army if the prince ever set foot in the principality again."

Pierre's banishment was lifted soon after and he received an annual payment to support him after the divorce.

Giving up the throne

In 1944, Princess Charlotte gave up her right to the Monegasque throne, passing them to her son, Prince Rainier III.

She later attended her son Rainier's wedding to Hollywood actress Grace Kelly in 1956.

She retained the title of Princess and went to college in her later life, obtaining a degree in social work outside of her royal duties.

In 1949 she saw her son assume the throne as Prince Rainier III of Monaco, then moved to an estate outside Paris to live out her later life.

There she helped rehabilitate convicts and lived with her lover, a former French jewellery thief, making her a rather unique royal figure in her later years.

Charlotte died in Paris in 1977, but is remembered in the Monegasque royal family through Rainier's granddaughter Charlotte Casiraghi, named for her great-grandmother.