Complex sentence: Sandino's only communication with Trincado was through a series of letters, but after his return, his manifestos and his personal affiliations were increasingly shaped by his attempt to apply the ideals of the EMECU.
Split into simpler sentences: Sandino's only communication with Trincado was through a series of letters. However, after his return, his manifestos and his personal affiliations were increasingly shaped by his attempt to apply the ideals of the EMECU.