Fore or not Fore?

Question

North & Hillard Ex. 230 includes the line: "By his advice the confederates bound themselves to resist to the death,". This, translated, in the Answer Book, as: "euis autem consilio socii se iureiurando obstrinxerunt fore ut usque ad mortem resisterent, "

My answer overlooked "fore"; but, fail to see its necessity. The deployment of "fore" with a past-participle usually creates a number of possible, but vague, alternatives eg., the confederates had been about to bind themselves... Or, the confederates would (a subjunctive may be used for this) bind... Or, the confederates were likely to bind... The past-perfect "obstrinxerunt" is definite in its meaning (as the English appears to demand) so why blunt the intention by rendering it vague with "fore"? Essentially, what is the use of "fore" achieving here?

Thank you.

Answer 1

You need the subordinate idea ('to resist to the death') to be cast into the future (because the confederates didn't bind themselves to have resisted earlier or to be resisting right now). Normally, you'd say obstrinxerunt se usque ad mortem xxxuros esse, where xxx is the (stem of the) future active participle of the verb resistere. However, resistere is one of a number of verbs that lack a future active participle. Therefore, to arrive at a future of this verb in an accusative+infinitive construction, you have to use the periphrasis fore [= futurum esse] ut + subjunctive to 'simulate' it. Literally, then, you end up saying, 'They bound themselves that it would be the case that they resist to the death.'

This is discussed in Allen & Greenough, §569.a.