Defend the Castle

Defend the Castle is a quest in Fallout 4.

Quick walkthrough
Defend the Castle Objective: Go to the Castle and defend it after you build the defenses.

The Institute synths are planning to attack the Castle. Keep in mind that you need eight Settlements for this quest to begin. You can listen to Radio Freedom for information related to the attack. Defend the Castle and speak with Ronnie and Preston afterwards.

Detailed walkthrough
This quests consists of "waves" where a limited number of attackers will spawn and attempt to take over The Castle.

Brotherhood of Steel -Waves consists of 1 vertibird and its occupants which put together, consists of a total of 10 vertibirds.