Circle the wagons
Definition 1 of 2
Pro Tip 1/3Team Defense
Implies teamwork against challenges, not physical defense. 
When the company faced bankruptcy, employees circled the wagons to brainstorm saving strategies.
Pro Tip 2/3Crisis Unity
Used when a group needs unity to deal with a crisis or attack. 
The community circled the wagons after the flood to support each other.
Pro Tip 3/3Not Literally
It's metaphorical, not suggesting to physically form a circle. 
The class circled the wagons to finish the project overnight.