Hello Ben - I have researched my own Sorrell line only back to 1766 with the baptism of Robert Haist Sorrell in the St. George in the East (London England) Parish Register.He was the son of Robert Sorrell, a gardener, and his wife, Elizabeth, and the family lived in Pennington Street, in that parish.
The name 'Sorrell' is of Norman French origin, and was introduced into England at the time of William the Conquerer in 1066.The early Sorrell families appear to have settled in Essex and Suffolk counties.There was a later arrival of Sorrells in the 16/17th centuries when the Huguenots were fleeing France from religious persecution and many settled in London.
I believe my own Sorrells were from the later Huguenot arrivals in London.However, your own Sorrell line may well originate from the original Sorrell families in Essex.
There is a Sorrell crest:Gules, two lions passant guardant ermine.Which translated means the lions are emblems of Courage, Strength and Generosity.The fur ermine was considered the perfect emblem of Dignity and gules (red) denotes Military Fortitude.
I think you are right in thinking that many Sorrells were military men.My own father, now deceased, was a Major in REMEHis father was an Engineer in the Royal Navy, and an earlier ancestor was Joseph Sorrell who, whilst serving in the 10th Hussars, died in Jallalabad, Afghanistan, on 7 June 1879, at the age of 28.
I have a rough print of the Sorrell Arms, the original of which is in the Society of Genealogists Library.If you like I could scan and send this to you.