"Oh well," said Henrietta, "I’ve something to find out too!" And Isabel saw that she had not renounced an allegiance, but planned an attack. She was at last about to grapple in earnest with England. (53.17)
Although Henrietta plans to marry an Englishman, Mr. Bantling, she certainly doesn’t intend to give up her American identity – Isabel realizes that her friend is characteristically ready to take on England, rather than give in to it.