The Lord was opposed to the Amalekites for two reasons. Firstly, they were a wicked people (1 Samuel 15:18) and thus deserving of God’s judgment.1 Secondly, they were opposed to Israel and constantly sought to destroy God’s people (see Exodus 17:8–15; Deuteronomy 25:17–19; Numbers 14:43–45; Numbers 24:20; Judges 3:13; Judges 6:3; Judges 10:12; 1 Samuel 14:48; 1 Samuel 30:1; 2 Samuel 8:12; Psalm 83:2–7). As a result, the Lord pronounces herem or the ban upon them (see Leviticus 27:28; Deuteronomy 20:16–18); this is the only occurence of this Hebrew term in Samuel.2 The herem involved destroying all people, and sometimes animals (livestock were not always included under the ban, Deuteronomy 2:34–35; Deuteronomy 3:6–7; Joshua 8:2; Joshua 8:26–27; Joshua 11:14) thereby devoting them to the Lord.3
3 Now go and strike Amalek and devote to destruction all that they have. Do not spare them, but kill both man and woman, child and infant, ox and sheep, camel and donkey.’”