〜べくしてV（た）

Means "there was an inevitability for it to turn out so, and it naturally turned out so." It states that it was not by chance, but a natural consequence in which the conditions that ought to occur had come together. The same verb is repeated; the basic forms are 「なるべくしてなった」「起こるべくして起こった」. This is a different usage from the 「べく」 that expresses purpose or volition (〜するために).