In copying this passage from 𝓞 into 𝓟, Oliver Cowdery initially wrote “and they could not overpower us”. He was undoubtedly influenced by the preceding use in this passage of the first person (“after we had dwelt in the land” and “lest by any means my people should wax strong”). Almost immediately Oliver caught his error here, crossed out the us, and supralinearly inserted them (there is no change in the level of ink flow for the correction). Undoubtedly, the original manuscript here read them, not us. Moreover, the following conjoined predicate also uses the third person pronoun them (“and bring them into bondage”). A similar kind of confusion in pronoun usage is found later on in this same book:
Once more, the original text uses the third person pronoun them for “my people”, not the us that one might expect given the preceding use of the first person (“spare me for the Lamanites are upon us”). In this instance, the change to us was made in the 1906 LDS edition, and this us has been retained in the LDS text. For discussion, see under Mosiah 19:7.
Summary: Maintain in Mosiah 9:11 the third person pronoun them that is used to refer to “my people”; a similar example occurs in Mosiah 19:7.