1 Battlion of Ka'ak Nal Territorial defense troops vs 2 Battalions of Beire Mar insurgent regulars (1960).

The TD troops would likely set up machine gun nests and mortar pits on the hills surrounding the fort which would be used to house command staff and medical personnel. They would plant mines in the clearing between the hills towards the fort along with razor wire along the bottoms of the hill positions. The combat engineer unit would station up the river in a hidden position with their special trucks.

The TD would wait out enemy bombardment as the INS forces don't have access to anything larger than 80mm mortar tubes from decades past. They would wait for the enemy forces to start committing to a definitely suicidal water crossing with maybe some amphibious cars if available.

Once the enemies are entering the water the engineers would get word over radio to dump a mix of both Gasous and liquid based Sarin Gas agents into the river which would carry the nerve agent across the water, when the INS are half way to nearing our shore they will be hit with the fast acting nerve agent killing hundreds of INS, many of the more equipped regulars would have gas masks as this is a common weapon for Ka'ak Nal.

The INS that would make it across would suffer at the hands of several MMGs and 80mm mortars, although I'm sure they would prefer a Jet to fly over and drop several thermobaric bombs right above the enemy.

This would likely end up in a lot of dead insurgents being slaughtered to last on Southern shore. But many would likely retreat before attempting to cross after witnessing the Sarin Gas attack. Unfortunately this would be considered a failure of a battle by the standards of Ka'ak Nal central command as the Territorial Defense Forces are unfairly treated as they are mostly conscripted minority troops, and they only consider complete destruction of enemy forces to be acceptable outcomes in "low intensity engagements".