Since the time of George Fox, Quakers have sought to avoid war or participation in wars.  The peace testimony remains one of the core elements of modern Quakerism, and is manifest in diverse activities of members of the Society of Friends in seeking peace and alternatives to violence.

Like all of the Quaker testimonies, it is a description of a commitment widely adopted by Friends, but not a creed or statement of belief required of members.  There is a story, based on oral traditon, which is frequently repeated among Friends regarding William Penn and George Fox.  Since the story does not appear in print until nearly two centuries after the supposed events, many doubt the historical veracity.  However, it does capture the spirit of more recent Quakerism.  The version below is from the earliest account by Samuel Janney (1852):

When William Penn was convinced of the principles of Friends, and became a frequent attendant at their meetings, he did not immediately relinquish his gay apparel; it is even said that he wore a sword, as was then customary among men of rank and fashion. Being one day in company with George Fox, he asked his advice concerning it, saying that he might, perhaps, appear singular among Friends, but his sword had once been the means of saving his life without injuring his antagonist, and moreover, that Christ had said, ‘He that hath no sword, let him sell his garment and buy one.’ George Fox answered, ‘I advise thee to wear it as long as thou canst.’ Not long after this they met again, when William had no sword, and George said to him, ‘William, where is thy sword?’ ‘Oh!’ said he, ‘I have taken thy advice; I wore it as long as I could.’

More information on the Quakers and peace, with links to many historical documents, is available from:

http://quaker.org/legacy/minnfm/peace/