Battering rams were effective siege weapons, used on gates or walls. Comprising a massive tree trunk — often mounted on a cart or suspended from a swinging structure, it repeatedly struck against fortresses with such force to crumble and splinter. Once a gape opened, attackers penetrated the city and engaged hand-to-hand combat.
How long it took to break open the walls or gates, depended on 1) the thickness and strength of the wall or doors, 2) the size of the battering ram, 3) the speed of the blows. The bigger the ram, the faster the blow, the more energy released. It was simply a matter of physics.
There must be a spiritual application of this. The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds. — 2 Cor. 10:4 NIV. Be patient in prayer; continue to strike against the devil, not with “vain repetitions” but with blow after blow of the battering ram. Hit hard. Don´t pray feebly. Pray forcefully, with faith and emotion. This moves God.
A goal sought after is like the siege of a city. It probably won´t be realized with just one quick-and-easy prayer. Stick to it. Realize that we are involved in warfare and the devil doesn´t cede easily.