A fantastic article on the potential influence of French military and physical education culture Okinawa Karate by Jean-Francois Loudcher and Christian Faurillon.
Loudcher, J.-F. and Faurillon, C., 2021. The influence of French gymnastics and military French boxing on the creation of modern karate (1867-1914). Martial Arts Studies, 11, pp.80–100. DOI: http://doi.org/10.18573/mas.135