Warder was a clubwoman with a strong interest in the war effort during World War I. She was active in the Cairo Women's Club, organized and led the Navy League of Cairo, and organized a Red Cross chapter for the city as well. In 1917 she worked with the women's section of the Illinois State Council on Defense. She was also a member of the state committee of Illinois's Equal Suffrage Amendment Association, and a leader in the United States Daughters of 1812 for the state.[2] She attended national conventions of the United States Daughters of 1812 and of the General Federation of Women's Clubs in 1916.[4]
Warder was 31 years old when she began training at the First National Service Training Camp for Women in 1916.[5] The following year she began preparing for overseas duty, to work in war camps and hospitals. In 1918 she joined the effort of the Women's Overseas Hospitals, as part of the Gas Motor Unit No. 1, to provide first aid in the trenches after a gas attack. However, on her way to France, she became ill, and died soon after arriving at Bordeaux, France, in a military hospital, aged 33 years, a casualty of the 1918 flu pandemic.[6] Her death was included in official casualty counts reported by the army, with her position give as "cook".[7] Gertrude Foster Brown, the Director General of Women's Overseas Hospitals, wrote a letter to Warder's parents, describing her last days, and her funeral service in Bordeaux. "Your daughter has given herself to her country just as much as if she had gone to the firing line, and I hope you will find some consolation in that thought. We have mourned her as if she were our own."[2] Warder's remains were returned to Illinois for burial with full military honors.[8]
