 Complete the following phrase:  Some republican Infantería de Marina units also saw frontline combat action; the 151 Brigada Mixta, was a mixed brigade composed of Spanish Republican Navy Marines led by Commander Pedro Muñoz Caro. Its landing operations activity was limited, however, by the lack of offensive actions and the general ineffectiveness of the Spanish Republican Navy. Therefore, these Republican Marines saw action mostly inland supporting the Army in such battles as the Battle of Alfambra, Battle of Brunete, 