Relevant legislation in England:
Bastardy Law & Maintenance Amendment Act 1872
Affiliation Orders Acts 1914, 1918 (Questions asked in Parliament 10th Feb 1915 & 1st March 1915 in reference to soldiers)
Bastardy Act 1923
Soldiers - an affiliation cannot be enforced in the usual way but by the Army Act 1881 (amended 1883, 1891, 1915). Similar legislation for sailors in Royal Navy. (Source: article on Affiliation in Encyclopaedia Britannica vol. 1)