Rattleneck was Caul Shivers’ father, and a chieftain who opposed Bethod. His eldest son was killed by Logen Ninefingers, even though he had promised mercy. Logen cut his arms and legs off, and nailed his head on Bethod’s standard. Rattleneck was never the same after his son’s death and died himself shortly before the events in the trilogy.
Bethod claims he had wanted to ransom his son back to Rattleneck.