Checked Vol 1 Nafziger. Nothing written except the Edict of 28 Dec 1813 raised a volunteer jager corps and the Order of 7 Jan 1814 raised a force of landwehr. No uniform details mentioned.
Some information on Napoleon series site. Link below.
link
The following information I think is on Hesse Kassel from the above link. I would question the quoted manpower numbers:
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The outstanding work "Die Achenbach-Bilderhandschrift 1813/14", published by Klaus Schäfer, Markus Gärtner, Alfred Umhey, Peter Wacker and Edmund Wagner, doesn't give a plate, but a page with remarks about the organisation and history of the Hessian-Darmstadt Landwehr.
The Landwehr was founded by decret of the 7th january 1814. All male Hessians, who didn't serve in regular troops or had other "society duties", were grouped into 3 classes:
1st class: all men aged 17 to 35; they should strengthen the regular troops
2nd class: all men aged 36 to 45; they should defend the country's borders
3rd class: all men aged 46 to 60; they should serve as a kind of security force within the borders of Hesse-Darmstadt
Organisation:
Until 1815 the Landwehr was organised into 3 "Provinzen" (regions), as well as the 3 (hessian) army corps.:
1st army corps: Provinz Starkenburg with 37.000 men (Commander: Justus Leonhard Freiherr von Follenius)
2nd army corps: Provinz Oberhessen with 47.000 men (Commander: Ludwig von Gall and Christian Zimmermann)
3rd army corps: Provinz Westfalen with 30.000 men (Commander: Friedrich Ferdinand Wilhelm Freiherr von Schäffer-Bernstein)
In total 114.000 men and 1.660 officers, who were organised in 45 regiments with 108 battalions and 492 companies. Some of the regiments had an own music corps!
Only combat: Siege of Mainz in February 1814
The Landwehr was dissolved on the 29th november 1819.
I hope, these informations are sufficient to get a first impression about these troops.
Nice regards
Markus Stein
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There is several Hesse Kassel landwehr plates in the NYPL. I know you are looking for Hesse Darmstadt information but the two states were generally linked 1814 onwards.
link
Hope this information helps somehow.
Michael aka WR