Boyd’s Bible Dictionary:

(sit) (Deut. 20:19). [WAR.]

From Manners and Customs of the Bible:

Ezekiel 4:2. And lay siege against it, and build a fort against it, and cast a mound against it; set the camp also against it, and set battering rams against it round about.
Several important operations in ancient sieges are here noticed:
1. The “mount” was an inclined plane which the besiegers of a castle or a walled town built up to the walls so that they could bring their engines of war closer, and work them to greater advantage. The mount was made of all sorts of materials, earth, timber, boughs, and stones, the sides being walled up with brick or stone, and the inclined top made of layers of brick or stone, forming a paved road up which the war engines might be drawn. Some of these engines are described in the note on 2 Chronicles 26:15 (#370); another is mentioned below. Mounts were used by the Assyrians, Babylonians, Egyptians, Jews, and Greeks, and are often referred to in the Old Testament under the name of “banks” or “bulwarks,” as well as “mounts.” See, among other passages, Deuteronomy 20:20; 2 Samuel 20:15; 2 Kings 19:32; Isaiah 37:33; Jeremiah 6:6; 33:4; Ezekiel 17: 17.
2. Dayek, “fort,” was a watch-tower. Numbers of these towers were set up before a besieged city, for the purpose of watching and harassing the inhabitants. See also 2 Kings 25:1; Jeremiah 52:4; Ezekiel 17:17; 21:22; 26:8.
The battering-ram is supposed to have been first used by the Phoenicians. It consisted of a heavy beam of wood strengthened with iron plates, and terminating in an iron head made like that of a ram. Suspended from a wooden framework by ropes or chains, the beam was swung to and fro by the attacking party, and was struck against the wall with repeated blows until a breach was effected. The Assyrian armies were abundantly supplied with similar engines of war, though they were made after different patterns. It is to these that Ezekiel refers in the text. “Some had a head shaped like the point of a spear; others, one more resembling the end of a blunderbuss. All of them were covered with a framework, which was of ozier, wood, felt, or skins, for the better protection of those who worked the implement; but some appear to have been stationary, having their frame resting on the ground itself; while others were movable, being provided with wheels” (Rawlinson, Five Great Monarchies, vol.1, p. 470).
To oppose the ram various inflammable substances, such as tow, were thrown upon the light frame-work, setting it on fire. To extinguish this, those who worked the ram carried a supply of water. Again, a chain was let down by the besieged, and the end of the ram was caught in it, and the force of the blow neutralized by drawing the ram upward. To counteract this some of the besieging party were stationed below the ram, and provided with strong hooks which they caught in the descending chains, hanging on them with all their weight.
Battering-rams were frequently used against walls from the ground, at the foot, but sometimes were drawn to the top of mounds such as have been just described. They are referred to, in addition to the text, in Ezekiel 21:22, and probably in Ezekiel 26:9, under the name “engines of war.” There may also be a reference to them in 2 Samuel 20:15.