You most likely cannot hold them accountable, unless you had a written employment contract for a definite time or period (e.g. a one-year contract) which they violated. In the absence of a contract, all employment is "employment at will," and an employee at will may be terminated at any time, for any reason, even reasons unrelated to their own job performance, without recourse. Just as your former employer could have terminated for, say, legal issues unrelated to your performance, so could your new employer.