Taking Independence

Taking Independence is a quest and achievement/trophy in Fallout 4.

Quick walkthrough
You must assist three settlements before Preston Garvey will approach you with this quest. He asks you to meet him at The Castle (Fort Independence) which was previously taken from the Minutemen. Upon meeting Preston and three Minutemen at an old run down store near Fort Independence, you go through some dialogue with Preston and the others before being prompted to choose a plan of attack (there are three options). After choosing one of the plans of attack, the others get into position before you engage the Mirelurks inside the courtyard of Fort Independence.

After clearing Fort Independence of the mirelurks, Preston asks that you clear the area of any egg nests. While you are clearing the eggs, the mirelurk queen spawns and you must defeat her. Once that is done, you are to clear the area of any remaining eggs, then meet the Minutemen in the middle of the courtyard where the radio transmitter is located. After searching the workshop within the Fort, you are to provide 10 power to the radio transmitter. Afterwards, talk to Preston Garvey and the quest is completed.

Detailed walkthrough
Once you have established approximately five settlements (counting Sanctuary) for the Minutemen, talk to Preston Garvey. He'll tell you about the Castle, the former headquarters of the Minutemen, and discuss his desire to retake the building to show that the Minutemen are back. Offer to help, and he'll tell you to meet him outside the castle.

It is strongly recommended that you bring power armor and at least one heavy weapon.

The hike to the Castle will take you through South Boston and past a number of both Raiders and Super Mutants in equal measure. Garvey is waiting for you in a destroyed Sullivan's west of the Castle with three other Minutemen. DO NOT APPROACH THE CASTLE BEFORE MEETING THEM. It is crawling with mirelurks and has nasty surprises in wait. Additionally, the Sullivan's has a bunch of equipment on the counter that may be useful--including land mines.

Talk to Garvey, and he'll discuss your options. The three Minutemen will offer various potential plans of attack--a direct assault into the courtyard via the breached northwest wall, a pincer through the breach and the main gate to the south, or setting up a firing line outside the northwest breach and drawing the lurks out to your guns. Pick whichever suits your preference, and then wait for the Minutemen to move into position. When all's in order, launch the attack.

There are about ten mirelurks of varying strength inside the Castle. Aim for their soft undersides, as chipping away at their shells is a sure way to just irritate them and get yourself clawed. Once they're all dead, Garvey and the Minutemen will observe the egg clutches laying around--if they're not cleared out the mirelurks will keep coming back.

Approaching the egg clutches will cause several of them to hatch mirelurk hatchlings at you--effectively radroaches. Either handle them as they come or take out the clutches from a distance. It is strongly recommended that before you begin clearing them out in earnest, you lay some mines on the breach in the southwest wall--not the one you came in on, the other almost-destroyed one.

The reason will quickly become obvious. After you've destroyed a few clutches, the entire Castle will shake, and a Mirelurk Queen will emerge from the lagoon--the "sea monster" that destroyed the Castle in the past. She'll make her way through the southwest breach and into the Castle courtyard. Try to keep a moderate distance--too close and she'll tear you to shreds, but too far and she'll spit acid at you with serious effectiveness. Keep up the fire and keep her attention away from your squishy allies, and she'll go down.

IN PROGRESS

Behind the scenes
The presence of mirelurks at the Castle may be an allusion to the [Lobsterback infantry that the [[wikipedia:Minutemen|Minutemen]] fought during the Revolutionary war. This could also be believed as there is a "queen" present, symbolizing the monarch. The queen is in the castle, which you must take.

Bugs
DO NOT CLEAR THE CASTLE BEFORE THE QUEST. if you do Preston Garvey will just tell you to focus on taking back the castle and cant continue don't know of a solution
 * Companion Preston Garvey will follow you around the whole game if you start, but don't finish the quest. However you will be unable to speak or interact with him. This essentially gives you 2 companions.
 * After defeating the Queen and clearing out the Fort, Preston Garvey will sit on the wall doing nothing with no speech options. This may be solved by sitting on the chair and waiting.
 * After killing the Queen, the remaining Minutemen become enemies and attack.