Sentence Correction (SC) | Re: Even though his army had never faced any defeat, the king Theodore car

If you want to use a past perfect, then the pastness should be deep and deep and not just before or just at the time of ending; in this case, the operation ending successfully and the advice given thereof are almost simultaneous. No Doctor will give advice after one month of operation.
The takeaway is to see the rationale and the worldly-wiseness ibehind the grammar rules.