Catherine Elizabeth Marshall (1880 - 1960) was a prominent British feminist and internationalist, and also a pacifist. With Schreiner and others, Marshall was one of the signatories to a letter of support for Sir John Simon’s opposition to the Bill to introduce compulsory conscription which was published in The Times in 1916. Among her many activities, Marshall was involved in the British Dominion Women’s Suffrage Union and in 1917 was invited to a BDWS lunch at which Schreiner was the star attraction. However, it is most likely that Marshall and Schreiner met in the activities around the formation of the Women’s League for Peace and Freedom and the No-Conscription Fellowship.
For further information see:
Jo Vellacott (2004) ‘Marshall, Catherine Elizabeth (1880-1961)’ Oxford Dictionary of National Biography Oxford University Press http://www.oxforddnb.com/view/article/38527