Usually we try to avoid conflict, but there's nothing better than a common antagonist to bring a team together. Minor differences between teammates immediately resolve themselves as the team rallies to overcome a common obstacle. All of sudden everyone becomes intrinsically motivated to win and even the complainers are willing to put in extra hours to fight. Feeling like you've been wronged is like being given a shot of adrenaline.
With heightened group cohesion, teams feel a greater sense of commitment to one another, leading to higher participation, satisfaction, and trust. Ideally, this starts a positive feedback loop where increased group cohesions leads to increased performance and vice versa.
I wonder if there are other ways to quickly instill this sense of urgency and unity that don't make people jaded. Deadlines help, but when they're overused they lose their potency.