‘ Joshua made war a long time with all those kings.'
All this took time. Only the highlights have been described in detail. But gradually Joshua's war of attrition succeeded. The last part of Joshua's life was taken up with it. Joshua 14:7-10 may suggest a period of five or so years but we must recognise that Caleb was using round numbers (note how often such numbers related to age end in nought or five. There was no specific calendar and it is doubtful if many accurately recorded the passing of any but the most recent ‘years', and ‘years' were anyway seen differently by different people).
Certainly five or so years of continuous warfare would appear to be a long time (roughly the same length as the second world war).