Which Secretary of State worked to secure the acceptance of Open Door Notes from major powers?

The correct answer is John Hay, who served as Secretary of State from 1898 to 1905. He is best known for his role in promoting the Open Door Policy regarding China, which aimed to ensure that all major powers would have equal trading rights in China and to prevent any one nation from monopolizing trade with that country.

In 1899 and 1900, Hay sent a series of diplomatic notes, known as the Open Door Notes, to major powers such as Britain, Germany, and Russia, urging them to respect China's territorial integrity and maintain an open door for trade. This policy was crucial in the context of the intense imperial competition in China at the time and helped to mitigate the threat of colonization by multiple powers.

Hay's efforts were vital in shaping U.S. foreign policy in Asia during this period, as they sought to establish American interests without direct territorial control. His advocacy for the Open Door Policy reflected the U.S. desire to enhance its economic influence while also maintaining a level of stability in international relations concerning China.