The dreadnought (DN) (dreadnaught) was a type of warship employed by most first-rate navies and some system-defense forces in the Post Diaspora era.
Dreadnoughts, along with superdreadnoughts (SDs) and battleships, were classified as ships of the wall, ranging in size from five to six point five million tons. Smaller and weaker than SDs, they were used when a star nation could not afford to build the larger ships exclusively, the Star Kingdom of Manticore prior to the First Havenite-Manticoran War. being an example, while other star nations operated dreadnoughts of Solarian design. The Republic of Erewhon being one such example as Solarian-designed dreadnoughts served in its Navy until at least 1913 PD. (HH8, Companion)
By the start of the Second Haven-Manticore War, the dreadnought continued in service with both the Royal Manticoran Navy and the Republic of Haven Navy, but the construction of new dreadnoughts had been suspended in favor of larger numbers of pod-laying superdreadnoughts. With the extreme lethality of missile combat during this period, dreadnought-sized vessels were considered simply too uncompetitive in terms of offensive and defensive capability to participate in the wall of battle, and the last Manticoran dreadnought was retired in 1921 PD. (HH10, Companion)
The Solarian League Navy continued to operate dreadnoughts into the second decade of the 20th Century PD, though none were employed in its war with the Star Empire and the Grand Alliance, and at least one of the League's System Defense Forces operated dreadnoughts in 1921 PD. (infodump, HH12, HH13, CS2)
Known DN Classes
Republic of Haven
Star Kingdom / Star Empire of Manticore