The Defence of Guenevere Lines 1-3

But, knowing now that they would have her speak,
She threw her wet hair backward from her brow,
Her hand close to her mouth touching her cheek,

• The poem opens the way you're told never to start a sentence: with the conjunction "But."
• The effect is kind of jarring – "but" suggests a contrast ... but to what? We don't know what came before.
• An unnamed "she" moves forward to speak because she knows an anonymous "they" want her to.
• Her hair is wet for some reason, and she has her hand on her cheek.
• We assume from the title that the unnamed "she" in this first stanza is Guenevere, but we don't know that for sure yet.