John immediately launched attempts to get his lands back - and ran into the Barons. He does run up a pretty good Navy though. And we hear of Roland the Farter.
The Barons Refuse to fight, 1205
1205 gave John a sneak preview of what life would be like later. Despite his begging and pleading, the Barons would not go to France with him in 1205 to fight for the French lands. There was a genuine feeling that they should not be made to fight abroad. There was also a general feeling of distrust between King and his barons. John relied on his household knights and servants, and was too paranoid to build any trust with his great magnates.
But after a winter of travelling round England, John managed to persuade his Barons to fight the following year. And the 1206 campaign is quite successful; John manages to re-establish his authority in most of Poitou.
The English Navy
Under John, the strategic situation changed back to the way it had ben under the Anglo Saxons - now the English Channel was no longer just a river between Angevin lands. To be safe, the king must control the channel. And to give him his due, John does just this. New Galleys are commissioned, squadrons formed, seamen employed, and an administration out around the Navy under William of Wrotham.