When C.F. Martin & Co. built their innovative large-body guitars in the early 1900s, they wanted to give them a name synonymous with enormity. So they were named dreadnoughts, after HMS Dreadnought, a World War I era British battleship.
Limited Edition LE-HMSD-2015 Battleship Dreadnought Guitar featuring a detailed painting of the HMS Dreadnought.
Completed in 1906, HMS Dreadnought was actually the sixth ship to bear the name, which was reserved for the most powerful battleship in the British Royal Navy. (HMS stands for Her/His Majesty’s Ship, a prefix given to many ships in the British Royal Navy.) But this particular ship was a significant departure from the old world battleships that preceded it. HMS Dreadnought was the first battleship of its size to be powered by steam turbines, making it the fastest battleship on the sea when it was completed. It also featured a massive gun array and was protected by thick steel armor. In 1915, it became the only battleship to successfully sink a submarine when it rammed the German U-29 (a scene depicted on the top of Martin's LE-HMSD-2015 Limited Edition Battleship Dreadnought Guitar, pictured in this post). The name dreadnought was subsequently used to describe the class of battleships based on the design of HMS Dreadnought.
So it’s no wonder that when C.F. Martin & Co. president Frank Henry Martin was looking for a name that evoked hugeness, he thought of HMS Dreadnought. His dreadnought guitars were larger and deeper than other guitars on the market at the time. The proportions were different as well, featuring a wider waist than previous models. From here, I’ll let Martin’s website take over:
The very first Dreadnought guitars (named for a class of World War I era British battleships, "Dreadnought") were manufactured by Martin for the Oliver Ditson Company, a publishing firm based in Boston. Curiously enough, the guitars weren’t sold with the Martin name on them, but rather were marketed in Boston and New York under the Oliver Ditson brand name, beginning in 1916. These Dreadnoughts did not even include a Martin serial number, but instead used Ditson’s own serial numbering system. They continued to appear in the Ditson catalog until the company’s demise in the late 1920s.
The Ditson Dreadnoughts were quite different in appearance from their modern offspring: The bodies were elongated to accommodate a wide, 12–fret custom guitar neck (12 frets clear of the body) with a slotted peghead. The early Ditsons also had a different soundhole rosette and inlay pattern, and had no pickguard. All of the Ditsons had mahogany backs and sides and spruce tops, like a modern D–18.
In 1931 the Martin Company began producing Dreadnought guitars that carried the Martin name. Two models designated D–1 and D–2 made their debut. The D–1, like the earlier Ditsons, was a mahogany body instrument, destined to become the D–18. With the D–2 (four were made in 1931) Martin introduced what may still be the most popular style of steel–string guitar, the rosewood body Dreadnought. All of Martin’s early Dreadnoughts had the 12–fret neck of the Ditson design. It wasn’t until 1934 that D–28s and D–18s officially were offered with the 14–fret neck most consider standard today.
Loved by guitarists for their huge sound and bass response, Martin’s dreadnoughts were (and still are) immensely popular, and the name stuck. While dreadnought started as a Martin-only descriptor, it has since been adopted widely to describe large-body acoustic guitars of similar proportions. Nearly every major maker has some variation on this classic guitar size.
Addendum: Dreadnought vs. Dreadnaught
While most makers use "dreadnought," an alternate spelling, "dreadnaught," is still fairly common. C.F. Martin, in fact, used this spelling on early dreadnoughts. From Martin Guitars, A Technical Reference:
Martin spelled it "Dreadnaught" until the early 1960s, and has used the "Dreadnought" spelling ever since.
We here at Elderly use the "dreadnought" spelling, which has been adopted by most guitar makers.