[1] Oliver's mother was Hawise (Hadwisa), a sister of Fulk FitzWarin.
In June 1216, he was in command of Wolvesey Castle when it was besieged by Prince Louis of France and the rebel barons.
[2][3] In April 1217, as Louis approached Dover Castle from the sea, Oliver and William of Cassingham attacked the small force which Louis had left behind after the failed siege of Dover in 1216.
In March 1218, he granted control of the estate of Hamedon until Eve de Tracy could reclaim by payment of sixty marks.
[7] With a group of English crusaders, he landed at the siege of Damietta in September or August.