In 1950, Kennedy Trevaskis, the Advisor for the Western Protectorate drew up a plan for the British protectorate states to form two federations, corresponding to the two-halves of the protectorate. Although little progress was made in bringing the plan to fruition, it was considered a provocation by Ahmad bin Yahya, the leader of the Mutawakkilite Kingdom of Yemen. In addition to his role as king, he also served as the imam of the ruling Zaidi branch of Shi'a Islam.