Liddle noted that beyond imposing a delay, the German policy of unyielding defence and counter-attack failed and ought to be judged on the same terms as British and French methods. Haig and Joffre were right to believe that a serious German collapse was possible until late July and no convincing alternative to attrition, in the circumstances of late July to early September, has been proposed. Analysis of captured documents and prisoner interrogations, indicated the strain being imposed on the German army. Philpott criticised the weeks of costly, small, narrow-front attacks against a skilful and determined defence by the Germans, yet Gallwitz "had no better tactical method", which reduced operations to a battle of wills. In the Fourth Army area from counter-attacks were made against attacks, exposing German infantry to similar costly and frustrating failures. German artillery and air inferiority was a great disadvantage and led to constant losses.