OH TO SEE THE LORD GOD

In 1450 BC Amalek fought with Israel in Rephidim - in the wilderness after their exodus out of Egyptian bondage (Exodus 17:8). Four hundred and sixty years latter (1050 BC) the LORD, in remembrance of this deed of the Amalekites, instructs King Saul, of Israel (their first king), to go to war against Amalek and destroy all peoples including women and children, and all livestock.
God had not forgotten nor overlooked what the Amalekites did to His people ion the wilderness - and had told Abraham, yea, had promised Abraham, He would curse all those who cursed Israel (Abraham's seed). GOD had proven Himsaelf faithful to His word once again in keeping this promise. He also proved His love for His own in that any who would dare to harm the children of GOD would some day feel the wrath of GOD come down upon them.
God is the protector and avenger of His own. In fact He states in Romans 12:19 "Vengance is mine saith the LORD, I will repay." and again in Hebrews 10:30 He makes a similar statement [which is actually a quote from Deut. 32:35, in a song spoken by Moses to the Israelites], in which is declared that GOD iin deed would avenge His people in "due time."