Edward Eliot, 3rd Earl of St Germans, Conventions concluded, under British Mediation… (1835)
“ ART. I. The Commanders-in-Chief of the two Armies now engaged in Hostilities in the Provinces of Guipuscoa, Alava, and Biscay, and in the Kingdom of Navarre, agree to preserve the lives of all Prisoners who may be made on one side or the other, and to exchange them as stipulated below. Periodical exchange of PrisonersART. II. The exchange of Prisoners shall be periodical, twice or thrice in a month, or oftener if circumstances should require or allow it. Number of Prisoners exchanged to be equal. ”
