Wallace wrote on other social and political topics including his support for women's suffrage, and repeatedly on the dangers and wastefulness of militarism. In an essay published in 1899 Wallace called for popular opinion to be rallied against warfare by showing people: "...that all modern wars are dynastic; that they are caused by the ambition, the interests, the jealousies, and the insatiable greed of power of their rulers, or of the great mercantile and financial classes which have power and influence over their rulers; and that the results of war are never good for the people, who yet bear all its burthens". In a letter published by the Daily Mail in 1909, with aviation in its infancy, he advocated an international treaty to ban the military use of aircraft, arguing against the idea "...that this new horror is "inevitable," and that all we can do is to be sure and be in the front rank of the aerial assassins—for surely no other term can so fitly describe the dropping of, say, ten thousand bombs at midnight into an enemy's capital from an invisible flight of airships."