50 Centimes - Chambre de Commerce de Bayonne 64

French chambres de commerce were authorized to issue emergency small-denomination notes during World War One specifically to address the acute shortage of coin — silver and bronze had been hoarded or melted almost immediately after mobilization in August 1914. Bayonne's chamber, serving a mid-sized commercial port in the Basque Pays, was among dozens of regional bodies that stepped in to fill that gap from 1915 onward.

The JP#21-24 through 28 grouping covers multiple emission variants across the series — date differences, signatory changes, or minor typographic variations account for the five distinct picks under a single design family.