The tenth child of the Landgraf of Hessen-Kassel, she belonged to a traditional Protestant family, but one subsisting on hiring out armies. Her eldest surviving brother, Friedrich, took for a second
wife Ulrike Eleonore of Sweden. Through his wife he became King of Sweden in 1720. Then, in 1730 when he became Landgraf, a younger brother, Wilhelm became regent and eventually, in 1751, Landgraf in his own right.
Marie Luise, shy and goodlooking, was mentioned as a possible bride for the Prince of Orange. Accordingly, the Prince came to "inspect" her, but not for long as he had to return to the war. For about a year-and-a-half they corresponded rather formally; then, on 26 April 1709 in Kassel, they married. However, almost immediately he had again to return to the war, and for a while she remained in Kassel. After eight months she moved to Leeuwarden, Friesland. Very soon she became very popular, even more so than the Dowager Princess, her mother-in-law.
When her husband yet again returned to war, she had the company of her mother-in-law and five unmarried sisters-in-law. However, a sixth one, Sofia Hedwig, after hardly two years of marriage was sent home and divorced by her tyrannical husband, the Duke of Mecklenburg-Schwerin who, after again divorcing a second wife, married Catharina Ivanovna, Grand Duchess of Russia.

While at war, Johan Willem Friso received the news of his wife's pregnancy and, on 23 October 1710, a daughter was born. Her mother-in-law, together with all those unmarried sisters-in-law, moved to Oranienstein, a family property in Germany, leaving Marie Luise rather lonely in Leeuwarden. With the inheritance of a distant relative, the Prince of Nassau-Hadamar, and the increasing popularity of her husband, their future started to look more fortunate.
Marie Luise was seven months pregnant when she last saw her husband. On his way to meet the Prussian king, he had to cross a river when a sudden cloud-burst capsized the boat and the Prince was drowned on 14 July 1711. It took two days for the news to reach Leeuwarden and eight days before the prince's body was found. As well, less than a month before on the 16 June 1711 she had also lost her own mother.
At least her father came to be with her when her baby was due. Her mother-in-law also came, but was no support as she wanted to usurp Marie Luise's position as regent for the new-born baby, a son, Willem IV. After a while, the Friesians declared that they wanted Marie Luise. Consequently she was made regent from 1711 until 1731. In the beginning she began to economise and so after a while, to contribute towards this, her mother-in-law returned to Oranienstein. At first she was regent for only Friesland; but later also for Groningen, Drente and Gelderland to add to her responsibilities.
Religious and serious, she earned the love of her people and became known as "Marijke Meu" (Aunt Mary). Her daughter, the 16 year-old Anna Charlotte Amalia, left her to marry the Hereditary Prince of Baden-Durlach; but less than five years later she, too, would be a widow with little children. With his coming of age, her son took over, allowing her to return to Kassel for a visit to her own relations.
Three years later her son married the English Princess Royal Anne.After seventeen years, and again with only one surviving son and daughter, Willem IV died. For the next eight years, her daughter-in-law acted as regent for Willem V, Marie Luise's grandson. Then, with the death of her daughter-in-law, Marie Luise had to return as regent once more in Friesland. This time it lasted from 1759 until her own death on 9 April 1765, in Leeuwarden, at the age of 77.
 

Source: Leo van de Pas