In The Crucible, how is Abigail able to control the girls?

Abigail is clearly a young woman of great charisma and
strength, as is seen in Act 1. She knows what is at stake now that her Uncle, Parris,
has seen a group of girls dancing naked in the woods and that it could mean whipping or
worse for her. We see Abigail's desperation but also her implacable strength of
character that forces the girls to bow to her commands. Note how in Act 1 she "furiously
shakes" Betty to get some kind of response from her. It is when Betty shouts out what
Abigail did that we see Abigail's true colours:

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You drank a charm to kill John Proctor's wife!
You drank a charm to kill Goody
Proctor!

At this point
Abigail "smashes her across the face", screaming "Shut it! Now shut it!" She quickly
works to assure everyone of the "truth" to try and limit their
punishment:

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Now look you. All of you. We danced. And Tituba
conjured Ruth Putnam's dead sisters. And that is all. And mark this. Let either of you
breathe a word, or the edge of a word, about the other things, and I will come to you in
the black of some terrible night and I will bring a pointy reckoning that will shudder
you. And you know I can do it; I saw Indians smash my dear parents' heads on the pillow
next to mine, and I have seen some reddish work done at night, and I can make you wish
you had never seen the sun go
down!

This, then, clearly
shows how Abigail maintains her control of the girls - it is through intimidation -
physical, mental and psychological, which induces terror in the girls and makes them
compliant to her commands. Note how in the rest of the play the girls always follow
Abigail's lead and never gainsay her.