Boy did I just luck out... Was playing Succubi in Masterwork. I got a caravan from my home civ in the fall. I know that fall is when the dwarves like to come around and mess with you, so I raised my drawbridge as soon as the merchants were inside... Or so I thought.
I missed one Wagon, and didn't notice until it had pushed itself against my Drawbridge in such a way that I couldn't lower it again. To let the wagon in, I had to dig around my raised bridge, making my dungeon vulnerable. My miners worked fast, the wagon moved through the alternate route, and I quickly cued up the construction of a wall to seal the breach. Literally a tick or two after I unpaused from ordering the wall to keep the dwarves out, the dwarves arrive.
I am in deep poop. I have no military yet. If the dwarves choose to go through the now unsealable and untrapped wagon entrance, my only defense would be my unarmored lumberjacks and miners. To my dismay, they choose that route over the trap corridor baited with chained troll.
This is where my good fortune kicks in. The caravan guard force, vastly outnumbered, steps forward and freaking annihilates the entire enemy force. My civilians, doing their stupid civilian gather/hauling thing, all decide to rush the battlefield, but the caravan guard is so effective, that all the dwarves are dead before they have the chance to introduce my ladies to the dwarven concept of FUN. Afterward, when un-forbidding the dwarven gear, I learned the outcome was never even in doubt. None of the invaders had any metal gear save for their weapons and accessories, and the Succubi guards were all decked out in the various forms of Bronze that they have access to.
...At this point, the panic subsides, and I remember that I had set up a second drawbridge specifically to cut the Depot off from the rest of the fortress. I had the foresight to plan for more or less the exact situation I faced, but not the hindsight to remember the plan, but for once the game decided to bail me out of my stupidity instead of punish it.