Ship types included in the wall definition included battleships, dreadnoughts, and superdreadnoughts. They were sometimes referred to as "wallers". Wallers participated as the main elements of a "Wall of Battle", with lighter elements being the "screen".
In Old Earth navies, "Ship of the Line" was a grouping of ship classes designed to participate in a "line of battle", where two opposing fleets would line up, bringing their entire broadsides to bear on each other. This led to a vast increase in the number of guns in a broadside, and established more rigid formations of ships. The "fighting instructions" was the term used for the tactic, which was formed in Britain to prevent a defeat like the one they had at Beachy Head. Ships fighting in a "line of battle" were common from the early 1700s CE, and did not stop being used until World War II.
Post Diaspora, due to the nature of space being three-dimensional rather than merely a two-dimensional ocean, allowed for the development of a Wall of Battle, with ships forming up both side to side, and up and down as well, in order to bring the maximum amount of broadside weapons to bear on an enemy formation. (HH3)
- The Short Victorious War - Appendix: Honor Harrington's Navy, Naval Design and Doctrine