She collected over one million signatures, signed by supporters from the US, UK, and Germany, for a proposal she had written prior to the second peace conference in The Hague.

She went on to collect six million signatures which she planned to present at the third Hague peace conference in 1914 but the outbreak of the First World War prevented this.

In 1909, Eckstein attended the second National Peace Congress in Chicago, USA, where she read a "World Petition to the Third Hague Conference".

From there she continued to travel to most European countries, and also Australia, New Zealand, Japan, and China, where she gained increasing support for her cause.

Amongst others, Eckstein worked with Bertha von Suttner, Alfred Hermann Fried, Ludwig Quidde, and Jean Jaurès.

She also published the book Staatenschutzvertrag zur Sicherung des Weltfriedens (State Protection Treaty to Preserve World Peace).

[11][12] After the end of World War I Eckstein worked with the Deutsche Liga für den Völkerbund (German League of Nations) and set up regional groups of it, including in her home town Coburg.

[4] In order to maintain awareness of the Kellogg–Briand Pact, she continued writing letters, and in 1942, she attempted to publish a manuscript titled "The Will to Power Harmonized", but the Reich Ministry of Public Enlightenment and Propaganda, under Goebbels, denied her permission.