With regards to your querry, I lately have been doing research on the uniforms of the American militias and regret to say that the F P Todd notes and albums do not have information on the uniforms of the Federal Blues, although they are a gold mine of information on the organization and uniforms of state militias. Nor have I so far encountered any other information on its dress. You mention Warren, Rhode Island, but, according to J J Richards, Rhode Island Early Defenders and their successors (East Greenwich, RI, 1937), the Federal Blues were "of Bristol, Capt. John Stockford, on the rolls until 1815." Mr Richards largely compiled this very useful study, which tries to trace every unit raised in the state, from the R I archives but it has no information on uniforms.
Another good source for the uniform of local units are the older town and county histories. These sometimes have a short history of the local unit and might describe its uniform. You might want to check the local or the state library regarding this.
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