The early years of the international Red Cross movement coincided with great technological changes in war medicine. The organizational peculiarities of the International Association for Relief of Wounded Soldiers in Campaign, set up by the Geneva Committee, and by the Red-Cross' national committees; the convergence in various professional conferences and publications of doctors from different national societies of this association; and the construction of a body of shared practical expertise tested during the Franco-Prussian War (1870-1871) provide keys for understanding the technological innovations introduced by the Spanish Red Cross during the third and last Carlist War (1872-1876).