What does it effect
Relative clauses in indirect statements usually have their verbs in subjunctive, relative and other subordinate clauses whose verbs are in subjunctive, provided that the subordinate clause is an integral part of the idea of the main clause
He set out for Rome in order that he might save from danger that city where his friends had gone
Romam profectus est ut illam urbem quo amici ISSENT periculo servaret
The general idea
. The verbs in such subordinate clauses are said to be attracted into the subjunctive by the verb that governs the larger construction