In Britain the parallel form Alice, derived via Old French, has historically been more common than Adelaide, though this form did gain some currency in the 19th century due to the popularity of the German-born wife of King William IV, for whom the city of Adelaide in Australia was named in 1836.
There was a medieval English form of this name, Helewis, though it died out after the 13th century. In the 19th century it was revived in the English-speaking world in the form Eloise.
This name can also be given in reference to the city in Italy, as in the case of Florence Nightingale (1820-1910), who was born there to British parents. She was a nurse in military hospitals during the Crimean War and is usually considered the founder of modern nursing.