I am in need of assistance

I fell victim to not reading a novel for a long time, then it becomes an inactive tab and then google generously deleted it.

My memory is a bit hazy but...

From what I remember, the MC is sort of a adviser/strategist. In a later/middle part of the story he was deployed somewhere with his troops to supposedly save/negotiate an exchange of POWs with the enemy forces.

There was even a part where he played psychological warfare with the enemy deligate by making his troops do some shooting practice. Making the enemy think that with each passing time, the MC's troops is shooting the POW's forcing them to make a rush decision.

Meanwhile the MC is deployed, the nobles were staging a coup d etat at the capital to overthrow the queen/empress. It was partly successful. The enemy even ambushed/bomb the MC's base of operation making people think he and his troops were dead. But of course they survived.

Having learned of the coup d etat, the MC retreated from his position and ordered the immediate marching of his troops into the capital to topple the traitors.

There was a part where he was blocked by a tank troops, but when they recognized him they joined him instead.

Then when they marched to the capital they were able to somewhat peacefully retake it.

If I remeber correctly the MC is like some officer in the military, but more so a strategic/resource manager type of role. He wanted to be honorably discharge from his position, so he tries to jeopardize his operation. Making his troops mine a plot of land, expecting to discover nothing but instead hitting an oil well instead, saving the empire from economic collapse