 In the 1220s Rögnvaldr formed an alliance with Alan , Lord of Galloway , in an attempt to fend off Óláfr . Rögnvaldr married his daughter to one of Alan 's sons , and it has been theorised that this son was intended to inherit the island @-@ kingdom . Rögnvaldr 's actions enraged the Manxmen and in 1226 they deposed him in favour of Óláfr . Rögnvaldr was later killed battling Óláfr in 1229 . 
