Archery was described by contemporaries as ineffective against steel plate armour in the Battle of Neville's Cross (1346), the siege of Bergerac (1345), and the Battle of Poitiers (1356); such armour became available to European knights and men at arms of fairly modest means by the middle of the 14th century, though never to all soldiers in any army. Longbowmen were, however, effective at Poitiers, and this success stimulated changes in armour manufacture partly intended to make armoured men less vulnerable to archery. Nevertheless, at the battle of Agincourt in 1415 and for some decades thereafter, English longbowmen continued to be an effective battlefield force.