Complex sentence: In all, some 3,600 cadets passed through Addiscombe during the years of its existence: of these, over 500 entered the Engineers, nearly 1,100 the Artillery, and about 2,000 the Infantry, some of whom subsequently transferred to the Cavalry.
Split into simpler sentences: In all, some 3,600 cadets passed through Addiscombe during the years of its existence. Of these, over 500 entered the Engineers, nearly 1,100 the Artillery, and about 2,000 the Infantry, some of whom subsequently transferred to the Cavalry.