Answer:
Ethos
Explanation:
Ethos refers to an appeal to credibility. In other words, the author wants to persuade readers to believe his arguments due to the expertise of those who propose them. In this case, Churchill argues that the people involved in this decision are "competent officers, well-trained in tactics and throughly up to date." Therefore, he wants to convince readers of his position due to the credibility of those who support him.
