Read the full text of Henry VI Part 1 Act 2 Scene 1 with a side-by-side translation HERE.
The scene starts with the French setting a watch on the walls of Orleans.
Talbot is planning a surprise attack, since the French have been feasting and are likely not to be on their guard. He's talking to Bedford, the king's regent or representative in France, and to Burgundy, a very powerful French noble who is on England's side.
Bedford says Charles is cowardly to accept a witch's help in battle: Charles must not be very confident in his strength if he needs hell to help him.
Burgundy inquires about Joan of Arc and Talbot says she is a maid or virgin.
Bedford doubts that a maid could be so warlike, in a classic example of the views of the period.
Burgundy says Joan may prove masculine, especially if she carries armor.
Talbot says oh well, if the French want to invoke evil spirits, that's their problem; the English will trust in God as their fortress.
The English agree to split up and attack Orleans from several places.
The English call out to St. George, the patron saint of England. This is sort of like trying to get Obi-Wan Kenobi on your side.
The sentinels aren't asleep, and they do notice the English, so the French lords are surprised instead and have to leap over the wall to retreat half ready. It's like turning up to class with your dressy Oxford shirt and your Mario pajama pants.
The French say how desperate and bold the attack is, and wonder whether Talbot might be "a fiend of hell" (2.1.49), or supported by heaven. Either way, his success seems supernatural to them.
Charles and Joan come in together, which is maybe a little suspicious since it's the middle of the night. Have they been in bed together? Or have they been virtuously keeping guard on the walls? Hrm…
Charles turns on Joan and asks if she wanted them to succeed a little only to lose a lot. He's pretty fickle, given that he was just promising to make her the patron saint of France.
Joan asks why he is so impatient and says her power isn't always at the same level; she blames the French military for not keeping a better watch.
Charles blames Alencon.
Alencon says his area was fine—what about the other leaders?
The Bastard says his quarter was secure, too.
Reignier gets in on the action and says "Mine, too."
Charles says he's spent the whole night walking around and helping the sentinels, and asks how this could have happened.
Joan says it won't really help to figure out why it happened—they should get going and fix the problem.
An English soldier comes and chases them off. Embarrassingly, they leave their clothing, or at least some of it, behind, so the English soldier takes their things. This has got to be pretty humiliating for France: A soldier who doesn't even get a name in the play is taking spoils from the King and his closest advisors.
The soldier points out that Talbot's name is just as good as a sword: It scares the French off. Good thing the French nobility is already gone. This would be pretty awkward if they were around to hear it.