Use "iron heel" in a sentence

1. The call of the Wild (1903); The Sea Wolf (1904); The Iron Heel (1908); Martin Eden (1909); etc

2. Let us be content to wait until we have redeemed ourselves from the evils of 250 years of servitude by the improvement of the advantages that God has so graciously brought to our door, before we venture into that dark continent from which our fathers were torn, to be ground under the iron heel of the slave-master