Had a pretty epic fight with voidwalkers. Got lucky.
It is late summer, and the human caravan arrives in the south. However, in a disastrous turn of fate, a bog troll theif spawned right next to it, and slashed the leading merchant and his head off, causing their swift departure. I forbid the items there till I can dig a safe, underground passage to the loot site.
I wait a couple seconds, and a western Nephilim caravan appears, making a beeline for my fortress. However, barely two seconds past when the backdoor entrance came the screams of a marksdwarf - voidwalker! They had ambushed him as he was taking a stroll through the woods (off to send off a message raven to his elven leaders, the sympathizer). He is quickly dealt with, for I have not equipped him with bolts. I ordered the backdoor bridge to be pulled. Here's the brilliant stroke of luck. The delay allowed half the voidwalker foot to step upon the bridge, which immediately raised and atom smashed them. This was key to the resulting battle.
With the back entrance no longer an option, the ambush force leader, a cavalry destroyer mounted on a giant lion circles along my western side of the fortress to get at my south west causeway. This means they pass through the western bunker loaded with 15 novice marksdwarves. I see their numbers, 7+ on foot 1 on lion. I decide it's still risky, and decide to pull the causeway bridge. The bulk of the forces shrug off the blows of the unskilled marksdwarf battalions, who only managed to stop the cavalry soldier by shooting down his lion, and the large force of voidwalkers are nearly past the bridge when it closes, throwing 3 off the causeway. I decide to let the marksdwarves continue shooting them while the sat there unsure what to do. However, I quickly notice the Nephilim caravan, oblivious, was heading towards the voidwalker soldiers. I decide to make a sally with my armored speardwarf squad, so as to prevent harm to the lovely steel trading angels. I lower the bridge and crush the majority of the remaining voidwalkers foot. The soldiers rush forward.
The leader, Ning charges forward and engages two of the voidwalkers with marksdwarf support while his two students took on another one. Ning killed one and fell off the causeway. At this point, I notice all the voidwalkers were over exerted and I order the unarmored (but armed with steel and tower shields) soldiers forward. They finish off the exerted voidwalkers, then surround the voidwalker on his unconscious lion, where he is poked full of holes by iron and steel spears.
So ends the first voidwalker encounter. While it felt great, and sort of like a mid-movie victory where after the battle, theres party and trading, you can't help but worry for the big battle later on. I mean, I barely stood a chance with an ambush squad. What if a full on elimination force greets me in a year? Here's hoping I can get the soldier's skill and equipment up.
As I fiddle right now with the bridges and burrows and clean up, I hear a disturbance, and it appears a voidwalker who was on the backdoor bridge, got flung up to the roof, and made the mistake of attacking the western bunker. He is currently being pin cushioned.