Thank you all for your rapid responses to my query. I am now working on getting back to that area of the scenario to see what is happening. It will take me quite a while, if I manage to hold on that long against the aggressors.

That was in scenario 015 of mod 1.50. It is now academic since I did an upgrade to 1.80 and consequently lost the saved game. Thank you for your reply.

<t> I have been running a solitary scenario from the Japanese side. I have isolated and conquered Chungking, capturing 76 enemy units. When I tried to advance my troops from Chungking against Yunan and Chengtu, the game does not allow it, implying that there are still forces in the city of Chungking ...