The phrase "were back of" can have several synonyms, depending on the context of its usage. If it denotes support or encouragement, synonyms such as "backed," "assisted," or "bolstered" can be used. If it refers to the position or location of someone or something, synonyms like "behind," "rearward," or "trailing" can be suitable. In terms of motivation or drive, you can replace "were back of" with "pushed," "urged" or "nudged." Ultimately, the choice of synonym depends on the intended meaning of the sentence and the tone in which it is spoken or written.