John spent much of 1205 securing England against a potential French invasion. As an emergency measure, John recreated a version of Henry II's Assize of Arms of 1181, with each shire creating a structure to mobilise local levies. When the threat of invasion faded, John formed a large military force in England intended for Poitou, and a large fleet with soldiers under his own command intended for Normandy. To achieve this, John reformed the English feudal contribution to his campaigns, creating a more flexible system under which only one knight in ten would actually be mobilised, but would be financially supported by the other nine; knights would serve for an indefinite period. John built up a strong team of engineers for siege warfare and a substantial force of professional crossbowmen. The king was supported by a team of leading barons with military expertise, including William Longespée, William the Marshal, Roger de Lacy and, until he fell from favour, the marcher lord William de Braose.

John spent much of 1205 doing what?