Was born a German Prince with connections to the British Royal family through his father's cousin Prince Louis of Hesse who had married Princess Alice, Queen Victoria's daughter.  He was naturalised as a British subject in 1868 when he joined the British Royal Navy at the age of 14.  He served deployments on numerous royal tours during his early naval career.

After 40 years of service in the British Royal Navy, Prince Louis became the British Admiral of the Fleet and First Sea Lord and was responsible, with Winston Churchill, for the total mobilization of the fleet prior to World War I.  He was later forced to step down from his role due to anti-German feelings.

Relinquished his German titles and the name Battenberg in 1917 at the request of King Gearge V in order to help reduce the connections of the British Royal family with Germany.  He became known as Louis Mountbatten, First Marquess of Milford.  Each of his immediate family members also renounced their German titles and adopted the surname Mountbatten.