Ok, close in my troops onto their borders. Prepare 30 ships for sea travel. Set sail for the enemy's northernmost fleet as soon as possible, meanwhile, I want my army to distract the enemy defenses by launching an artillery attack and some minor infantry assaults. As for the fleet, give the enemy coast a WIDE berth, they musn't be seen.
Fortifications and command posts are being built and a port has been established
The task force has tried to infildrate but the trench lines are already covering their entire border and 20k men are manning it with more being trained and deployed by the month, only 6 men who tried to sneak past at night were lucky enough to be able to move after being barraged by artillery and shot by machineguns and rifles alike. This was in large matter due to most of the land nearby either being flat or made flat
In the new highlands north of the desert, begin building a port to host the mining district's residents and workers.
Meanwhile, have the rest of my colonial army begin building fortifications and forward command posts.
Send a task force of a few hundred covert troops into the enemy territory. Have them ambush a smaller enemy group, a patrol or minor division perhaps, kill the soldiers and colelct as much enemy equipment as possible, return back to main military headquarters for reverse engineering.
Alright 50 ships have been built
Send them a message, they have 1 last chance to agree to the rather light tribute.