At its peak the total of shield volunteers in Baghdad numbered about 500, but the realization that the thousands needed to have a chance of stopping attacks on Baghdad had not materialized, combined with the failure of the United Nations to forestall war, meant that bombing was imminent.[citation needed] Many of the shields chose to stay; many others chose to leave. Still others, like O’Keefe, were ordered out by the Iraqi government. One 21-year-old human shield, Tom Hurndall, left Baghdad for reasons of safety.