Martin 0-18K guitars are relatively common in the period from 1918 to 1934. The 00-18K guitars on the other hand are quite scarce, only 55 were made from 1918 to 1925.
Serial number 14156 was stamped on October 1, 1919 and was shipped to Sherman, Clay & Co. in San Francisco CA on Novermber 1 that year.
Like many early guitars meant for Hawaiian playing, this guitar has fan bracing instead of X-bracing. Eventhough this guitar was made for Hawaiian playing that did not include a flat fingerboard with a raised nut and saddle. On early Hawaiian guitars Martin regulated them for gut strings and supplied a nut extender for Hawaiian playing. The saddle, however, was not changed.
The tuners are Dinsmore & Jager (D & J) #5 brass machines with ivoroid buttons.
Style 18 koa guitar features:
Back and sides: Koa
Other period features:
Dot fingerboard inlays
Macassar ebony pyramid bridge
C. F. Martin & Co. stamp on back of headstock
No style stamp
my ’20 0-18K  has tuners like the brass/yellowed-button ones on this’n. I’ve X-lt Da’dds on it tho’ I sub a heavier Big E string for the dropped/open tunings this gtr mainly sees. I’ve always found it fascinating that these “earliest Martins meant for steel [‘Hawai`ian style use] strings” are fan-braced.