institution
aries
battering ram
also: ram
The aries: a battering ram, the heavy beam swung to break down a wall or gate; touching it to the wall marked the point of no return for surrender terms.
Reading notes
- The Gallic War §2.32.1 ram
The battering ram (aries): once it touched the wall the assault was held to have begun, so surrender had to come first to win terms.