This bastion is called Nedre platt and becomes brutally attacked in the last siege that Bohus has to endure. Bohus has now been Swedish since 1658, but Norway does not give up so easily. In 1678, the Norwegian Governor Ulrik Fredrik Gyldenlöwe attacks Bohuslän with about 4000 men to take Bohuslän back to Norway.

The Norwegian Gyldenlöwe sends a letter to the Swedish lieutenant general Harald Stake. He threatens that it will only be a matter of time before the castle is taken over and that they will spare the Swedes’ lives if they just lay down their arms. This letter is received with contempt by Harald Stake who, sitting on the commode, writes the following:

Sitting, shitting, I recieved your letter.
The more I read, the more it drift.
The ground was bare, there weren’t any leaves.
So I used your letter to whipe my arse.

Annoyingly, the attack must be stopped as diseases ravage the Danish-Norwegian army. Two years later, on May 20, 1678, Gyldenlöve returns, now with almost four times as many men. They are now surrounding and shelling Bohus constantly for six weeks. Roughly 20,000 cannonballs, grenades and stink pots are fired at the fortress. The heaviest fire comes from the top of Fontinberget where the cannons have a good firing angle and the lower flat bastion ,where we now stand, is in the middle of the worst fire.

Inside, only about 900 men defend the castle, against the nearly 15,000 men who are outside! Prior to the siege, the Swedish officers had signed an agreement which means that a surrender is not even conceivable as they would then be considered traitors. But food, gunpowder and other necessities are now running low and the situation is becoming increasingly dire.

One of the flour stores in the castle church’s attic gets hit so that large portions of the last flour lay like a mist over the castle. Legend has it that the Swedes let their last cow walk back and forth here on the lower flat, lined with different cowhides to trick the enemy into thinking that there is still plenty of food.

Ultimately, Marshal Gustav Otto Stenbock comes to the rescue. Gyldenlöve realizes that the battle is lost and retreats north. Bohus once again withheld the onslaught for its final test and Bohuslän remained Swedish.