The date is established by the source, which describes the letter as having been sent to the foreign secretary, Gascoyne-Cecil, marquess of Salisbury, on ‘Saturday last’; the Saturday before 23 May 1878 was 18 May (Daily News, 23 May 1878, p. 2). The text of the letter was also published in The Times, 23 May 1878, p. 5.

The text of the declaration read: ‘We believe that there has not existed during the last twelve months, and that there does not exist now, any justification whatever for a war between Russia and Great Britain, and we should hold our Government guilty of the greatest crime towards this nation should they lead us, or allow us to drift, into war’ (Daily News, 23 May 1878, p. 2). An account of the declaration, which had been presented at a public meeting held on Clerkenwell Green on 14 April, first appeared in The Times, 15 April 1878, p. 11. CD had signed it by 1 May (The Times, 1 May 1878, p. 10), and on 4 May he was listed as one of those collecting signatures (The Times, 4 May 1878, p. 10). More than twenty fragments of unused printed forms for collecting signatures, later reused by CD for notes on movement in plants, are in DAR 209. Russia had declared war on Turkey in April 1877 following uprisings in the Balkan territories of the Ottoman Empire. Under the treaty of San Stefano, signed on 3 March 1878, the Ottoman Empire gave up its eastern European territory; the prime minister, Benjamin Disraeli, continued to urge British military intervention to prevent the establishment of a Russian client state with access to the Aegean. Renewed rumours of war following the call-up of reserve troops by Disraeli on 27 March, and the resignation on 28 March of the non-interventionist foreign secretary, Edward Henry Stanley, Lord Derby, prompted the delivery of 189 petitions to Parliament between 5 and 26 May (Saab 1991, pp. 158, 184–9). For the politics of the war and the debates within government, see Hicks et al. eds. 2012, especially pp. 18–28. See also letter from T. H. Farrer, 29 March 1878, and letter to T. H. Farrer, 7 May [1878] and n. 5.

Gascoyne-Cecil refused the request to meet a deputation. In a letter to Hugh Lupus Grosvenor, the duke of Westminster, on 20 May 1878, he replied that any statement the government felt at liberty to make would ‘necessarily be made to Parliament’, and urged the duke also to address to Parliament any arguments condemning government policy (The Times, 24 May 1878, p. 10).

Besides CD, the signatories include Charles Cecil John Manners, sixth duke of Rutland, Hastings Russell, ninth duke of Bedford, John Alexander Thynne, fourth marquess of Bath, Anthony Ashley-Cooper, seventh earl of Shaftesbury, Francis Thomas de Grey Cowper, seventh Earl Cowper, Thomas Stonor, third Baron Camoys, John Duke Coleridge, Baron Coleridge, Richard William Church, dean of St Paul’s, and Charles Lindley Wood.