Operation C tested an improvised Eastern Fleet

Operation C forced Britain into the multi-carrier battle it had anticipated, but without the strike carrier and numbers its doctrine assumed. Courageous and Glorious were already gone, leaving Formidable and Indomitable against five Japanese carriers. Somerville had only recently arrived, some air groups were not fully worked up, and much of the fleet had been assembled from dispersed trade-protection duties. A common exercise culture still gave senior officers and ratings procedures they could apply without long collective training. The Catalina report identified only two enemy carriers, so the planned night interception did not initially appear to face the full Kido Butai.