the first night your forced to loose when you place the 3 archers how your told to
Yes, the first night is made to be lost, it's the start of the story. The wall falls, you get Essence from it, and you use it in the Essence Tree to get stronger. From the next run on you can really hold the wall. I know it can feel unfair, so in the new update you can also skip the first night with the link at the top of the screen :)