Short answers, pulled from the story.
The document published on the 4th of October 1914 was titled To the Civilized World. It appeared just weeks after Germany invaded Belgium and France to counter negative reports in British newspapers.
Signatories included Wilhelm Röntgen who discovered X-rays in 1895, Hermann Emil Fischer who won the Nobel Prize in Chemistry in 1902, and Philipp Lenard who received the award for Physics in 1905. Ernst Haeckel also signed despite being a biologist known for coining terms like ecology and phylum during his career.
Richard Strauss refused to sign because he felt political declarations did not fit an artist. He stated such matters were inappropriate for creative professionals.
Astronomer Wilhelm Julius Foerster later regretted signing the original manifesto and joined forces with physiologist Georg Friedrich Nicolai to create a counter-document. Their Manifesto to the Europeans argued against the initial claims and remained unpublished during the war years until Albert Einstein brought it to public attention after the conflict ended.
A survey found that sixty out of seventy-six surviving signatories expressed regret by 1921. The New York Times reported on this aftermath revealing widespread disillusionment among the original group.