After retiring from a surgical career in Melbourne, she opened a field hospital, Hôpital Australien de Paris, in France during World War I, achieving the rank of Major in the French Army.

They received five responses, Grace Vale, Clara Stone, Margaret Whyte, and sisters Elizabeth and Annie O'Hara.

The women used their influence in the upper classes of Melbourne, to gain media attention, and petitioned the university council over the issue.

In July 2015, after gathering supplied and staff in Australia, Sexton established a tented field hospital, near Paris with financial support from her Australian colleagues such as Madame Charlotte Crivelli.

[5] Later in the war, Sexton, and Mrs Blackwood, worked at Val-de-Grâce, a military hospital in Paris where doctors mainly performed reconstructive surgery on injured soldiers.