Sir Bartholomew is an indispensible character. He is as essential to the novel as vassals and tenants were to feudal society. And like the army of "good vassals" he can get lost in the background, be overlooked or forgotten as flamboyant nobles and imperious princesses take center stage. But Sir Bartholomew is "the salt of the earth" and without him Envoy of Jerusalem would have less heart and less relevance.
On the one hand, Sir Bartholomew represents the "rear vassals" and household knights that were the backbone of army of Jerusalem. There were never more than a couple score of barons in the crusader states, and the feudal levee never fielded more than 1,200 knights -- including the militant orders. The bulk of those 800 or so secular knights were men like Sir Bartholomew, men with a small land-holding from which they earned enough to outfit themselves, a squire, and their horses. (Recent archaeology, by the way, has uncovered a number of "manor houses" for such knights, proving conclusively that the Latin elite did not live exclusively in the urban centers.) The importance of men like Sir Bartholomew was that they gave the Kingdom of Jerusalem a heavy cavalry capable of delivering a crippling blow on Saracen armies many times longer -- provided they were well led and the cavalry charge was properly timed and directed.
More importantly, however, Sir Bartholomew represents all fathers who have lost or have missing children. He embodies the terrible suffering of survivors of a catastrophe, which has carried away loved ones. He gives a voice to the spiritual doubts that all men feel when confronted with loss and grief that goes beyond what they think they can bear.
Sir Bartholmew's importance to the novel is enormous. He is a constant reminder of the human cost of defeat.