What action did George Curry take to save his men's horses?

George Curry's action to arrest the train engineer and drive the train to water for the horses reflects his leadership and commitment to the welfare of his men and their animals during a critical situation. Understanding the dire need for the horses to have access to water, especially in the context of the hardships faced during military campaigns, highlights Curry's quick thinking and resourcefulness.

This choice emphasizes the importance of logistics and the care required in maintaining troop strength and mobility, which were heavily reliant on the well-being of the horses. By ensuring the horses had water, Curry was not only safeguarding the logistical assets of his unit but also ensuring that his men would continue to have effective means of transport and support.

The other options do not accurately represent Curry's actions or context. For instance, leading a charge into Cuba or even not having a chance to reach Cuba does not address the immediate concern regarding the horses. Stopping the train and letting the horses graze, while caring in nature, would not provide the urgent solution needed to ensure the horses received immediate access to water. Thus, choice D stands out as the correct answer, underscoring the significance of proactive leadership in times of adversity.