1 Kings 14:30 - Ellicott's Commentary On The Whole Bible

There was war ... — Of such war we have no record, since the day when Shemaiah forbade Rehoboam’s invasion of the new kingdom; nor is there even mention of any action of Israel in aid of the Egyptian attack, although it is likely enough that such action was taken. The meaning may simply be that there was continued enmity, breaking off all peaceful relations; but in the scantiness of the record we can have no certainty that actual war did not take place, though it has found no place in the history.