The one thing they've been trying to prevent from happening all season has finally hit-and walkers are officially breaching Alexandria's walls in droves on The Walking Dead.

Glenn Is Alive!

After the guard tower fell and took one of the retaining walls with it, the horde that has been outside ever since the distraction from the Wolves led them to the town's location will begin to trickle in-and once they arrive, Alexandria will face its truest test in the face of the imminent danger the town has never known.

The entire community is at risk in a preview clip for the midseason finale, as the walkers invade the town and everyone is left to fight and defend themselves-or risk becoming another victim.

Daryl Lands In Major Trouble

However, the Alexandrians who aren't prepared to fight aren't the only ones at risk-Rick (Andrew Lincoln) and the rest of his group, including Michonne (Danai Gurira), Eugene (Josh McDermitt), Rosita (Christian Serratos), Carol (Melissa McBride), Carl (Chandler Riggs) , Maggie (Lauren Cohan) and more are all inside the town's walls as well-and there's no telling if they'll be able to save the place they've come to call home-and all of their new friends-without potentially taking a few hits to themselves as well.

And with several of their strongest fighters still on the outside-including Glenn (Steve Yuen), a now crossbow-less Daryl (Norman Reedus), Sasha (Sonequa Martin-Green) and Abraham (Michael Cudlitz)--the danger could be even more real and life-threatening.

The Walking Dead airs Sundays at 9 p.m. on AMC.