The newly formed New Zealand Parliament revised and expanded the Militia Ordinance, replacing it with the Militia Act 1858. Some of the main changes were clauses enabling volunteers to be included under such terms and conditions as the Governor may specify. The act also outlined the purposes under which Militia could be called upon, including invasion. Debates in Parliament had included expressions of concern about Russian naval expansion in the northern Pacific, pointed out that the sole naval defence consisted of one 24-gun frigate, and the time it would take for Britain to come to the colony's aid.