Maharaja Sajjan Singh belongs to the Rathore Dynasty and was the ruler of the princely State of Ratlam, which is now a district in Madhya Pradesh.
He was the only son of his parents and succeeded to the Ratlam throne at the age of 13.
In 1908, he was appointed as the Captain in the British Indian Army.
During 1914-1915, he had served the Western front in the first world war and because of his loyalty towards his service, he was given the honour of 11-gun salute to 13-gun salute.
After the first world war, he had served as the ruler of the State of Rewa for the two consecutive years i.e. from 1918 to 1922.
He had also served as aide-de-camp (an Army Officer who help officers of higher rank) to a General Commanding officer, George V and to the Prince of Wales (aka Edward VIII) during the period of 1915 to 1936.
From 1936 to 1947, he had served George VI as an honorary and as an extra aide-de-camp of his unit.
He was the connoisseur of Polo and served as Steward of the Indian Polo Association. He had also served as the Adviser and Member of the Selection Committee for Indian Army Polo Team.
He had married five times and had five children all with his fifth wife, Sodawala Maharani Shrimant Sodha Bai Sahiba.
He was also the Vice-President of Central India Rajput Hitkarini Sabha.
He had also recieved various honours such as Delhi Durbar Gold Medal (1903 and 1911), Victory Medal (1918), Silver Jubilee Award (1935), Coronation Medal (1937), and the Legion of Honour of France (1918), and many more.
On 23 March 2018, a film named, Sajjan Singh Rangroot was made, which is said to be loosely based on the journey of his life. The film starred popular Punjabi singer and actor, Diljit Dosanjh, who played the main character of Sajjan Singh.