You might want to begin by writing the state archives of Siracusa, the province which includes Pachino, and requesting your ancestor's military records. The worst that can happen is they will say no records were found...
Archivio di Stato di Siracusa
Via Tucidide, 24
96100 Siracusa (SR)
ITALY
email:
as-sr@beniculturali.itweb:
http://www.archivi.beniculturali.it/ASSR/You can use a letter similar to this:
03 maggio 2011
[your name]
[your address]
Archivio di Stato di Siracusa
Via Tucidide, 24
96100 Siracusa (SR)
ITALY
Egregii Signori,
Mi chiamo [your name here], ed abitare negli Stati Uniti all'indirizzo sopradetto.
Vi scrivo ora affinche mi aiutiate per fornire:
* FOGLIO DI CONGEDO ILLIMITATO
* REGISTRO DI LEVA
per i miei trisavolo:
* [great-great-grandfather's name, last name first, all caps] nato nel Comune di Pichino, data [date of birth or 'circa 1850'], paternità [his father's given name if you know it else 'incerto'], maternità [mother's full maiden name if you know it "SMITH JANE" else 'incerto']
Sarà mio onere il rimborso per le spese di uso del servizio e costi di spedizione. Mi faccia sapere l'importo corretto.
Distinti saluti,
[your signature]
Full names should be written in lastname firstname format in all caps, thus "SMITH JOHN". Dates should be written dd month yyyy with the month spelled out in all lower case (01 febbraio 1885). If you don't know the exact date, put "circa 1856".
"trisavolo" (or "bis-bisnonno") is great-great-grandfather, "bisnonno" is great-grandfather; "nonno" is grandfather.
Basically, the letter says,
Dear sirs,
My name is ... I live in the United States of America at the address above.
I am requesting the full military discharge records and conscription record for my great-great-grandfather who was born in ... on ... His father's name was ... and his mother's maiden name was...
I will be pleased to reimburse you for the cost of copying and postage if you will let me know the amount.
Sincerely,
You could try making the request by email; personally I prefer the formality of a written letter, but the state archives seem pretty goood about responding to email requests. The cost usually comes to just a few Euros.