The decline of Eli (the house of Aaron), Samuel’s beginnings, losing the Ark of the Covenant: 1 Samuel 1–4
The Lord of Heaven’s armies is, to our western minds, a strange thing to call God, yet this is who Elkanah takes his sacrifice to every year at the Tabernacle.
This name shows God as the all-powerful ruler of all of creation. It’s who Hannah asks for a child:
1 Samuel 1:11 O Lord of Heaven’s Armies, if you will look upon my sorrow and answer my prayer and give me a son, then I will give him back to you. He will be yours for his entire lifetime, and as a sign that he has been dedicated to the Lord, his hair will never be cut.
It’s also the same one whose presence goes with the Ark of the Covenant (for example):
1 Samuel 4:4 So they sent men to Shiloh to bring the Ark of the Covenant of the Lord of Heaven’s Armies, who is enthroned between the cherubim.
And it’s used in describing who set David on the throne, and it’s used by the prophets Isaiah and Jeremiah, and more than a few of the so-called ‘minor’ prophets in delivering justice to Israel for her sins, and later reestablishing Israel after the exile.
Amos describes God this way:
Amos 4:13For the Lord is the one who shaped the mountains,
stirs up the winds, and reveals his thoughts to mankind.
He turns the light of dawn into darkness
and treads on the heights of the earth.
The Lord God of Heaven’s Armies is his name!
This is who a childless women asked for a child.
More reading: Lord of Hosts: Lord of Heavens Armies?