The phrase "were obligation" can have a few different synonyms depending on the context in which it's used. If referring to a legal responsibility, possible synonyms include "duty," "responsibility," "requirement," or "mandate." If referring to a social or moral responsibility, synonyms could include "expectation," "obligation," "commitment," or "allegiance." In a more casual context, "were obligation" could be replaced with "had to," "needed to," "were required to," or "were supposed to." Regardless of the synonym used, the underlying idea is that there was some sort of obligation or responsibility that needed to be fulfilled.