Military Monday-Soldiers Claim Agency letter

One interesting letter found among the files my father gave me a while back is this one from the Soldiers Claim Agency.  This is a reply to my great grandfather Dennis McFadden who as far as I know is my only ancestor to fight on the union side in the Civil War. 

So far, I have not had any luck tracking down information about this agency and whether their files still exist or where they might be stored.  I would really like to have my g grandfathers original letter and any followup correspondence that may have occurred. 

I do have his record from the Civil War Pension Index but unfortunately the NARA did not have it in their files.  They did say in their response that it should be in their collection and that they would try to acquire it sometime in the future.  They referred my request to the Veterans Administration who have then forwarded it to a couple of different VA offices.  I'm still waiting to hear if they have been able to located the records. 

Letter transcription:

Dennis McFadden

Roscoe, PA

Comrade:

Your welcome letter rec’d.

Fortunately I found your discharge and enclose it to you.  Will you please acknowledge receipt.             

I am indeed glad to hear from you and shall enrol (sic) you name on our Regt. Register and will send you notice of our future meetings and shall hope to see you present.

Capt. Murphy is dead long since. Lt. Oldson was last heard from at Downs, Kansas. Lt. Dan Firestone was last heard from at Salem Columbiana Co. Ohio.

Write me when you want to know anything about 1^st Ohio Artillery. 

Had (?) you better let me get you a pension?

I can do it if anybody can.  I have been 30 years learning how (to do?) such work.

With a Comrades love

H.C. Miller