Wing Spar from a German
Fdh. G.III Friedrichshafen Bomber

This is an almost complete splice from the rear of the wing spar of a Fdh. G.III bomber measuring 14" x 3.25" x 2.5"  A faded ink inscription written directly onto the wood reads Morseau de fuselage de Gotha abatter le foret de Compiegne le 8 Mars 1918. Attached to the wood is a label reading Piece of a German Airplane brought down in the forest of Compiegne, France, March 8, 1918 The wood also bears a marking in ink "4-657."  In addition to my research, the former owner writes that the piece originated from the F.S. Terry War Museum in NELA Park, Ohio, which apparently closed down before or during WWII
The Fdh. G.III is shown below in a drawing by Ray Rimmel from the rear cover of his Albatros Productions' Windsock Datafile 65, Fdh G.III-IIIa by Peter Grosz. This drawing depicts an aircraft from Bogohl 5.

The spar cross-section matches the dimensions of the Fdh spar on page 7, shown below left, in the Croquis D'Elements D'Avions Allemands, the cover page of which is shown below right and dated July, 1919. 
The spar cross-section is shown below left and overlaid with the drawing from the Bulletin below right.  The spar was of the "rear spar of two and of the built-up box type made of spruce,"*  with a front and rear section glued together with small rectangular fillets top and bottom. The drawing suggests that the grains ran in opposing directions but the actual spar shows that they did not.  Indeed, it appears that the spar was a single piece of wood which was cut into two pieces and then glued back together.  Notice how the grain of the wood at the base of the lower left photo runs from the front to rear section. 

“These spares are of spruce and each half is furnished with several splices, so that the greatest single length of timber in them is not more than 14ft.  The splices, which occur in each half alternately, are of the plain bevel type about 15in long and wrapped with fabric.”

* Report on the Friedrichshafen GIII in the journal Aeronautics for 8 May 1918 and reproduced in Cross & Cockade Great Britain Journal Vol. 16. No.1 1985, p.3.

This is another photo sent to me by someone else who has a small piece of fabric from this aircraft (I apologize for not having written down your name and given you credit here)

The reverse sides of the first and third wreckage photographs are stamped Musee des Deux Guerres and the date was la nuit du 8 ou 9 Mars 1918. I also have a piece of fabric from this same aeroplane, item 4-654-2, as well as a brass bolt, 4-654-1.

Rick Duiven kindly informed me that this aircraft was from Bombengeschwader 5 / Bombenstaffel 6 and it crashed on return from a raid on Paris, falling over the Foret De Compiegne.  BG 5/Bs 6 stands for Bogohl or Bombengeschwader des OHL and Bosta or Bombenstaffel. The crew, all killed in action, consisted of Ltn.d.R. Otto Georg, Observer; Hptm.d.L. Fritz Eckstein, Observer; and Ltn. Leo Gerhard von Heydebreck, Pilot. 

Peter Grosz kindly wrote to me that as of 21 March 1918, Bogohl 5's staff were at Mouchin and Bosta 4, 5 and 6 were at Marquion.