The relative absence of Irish Catholic soldiers in England meant that the Ordinance was rarely acted upon. However, after the cessation of arms between the Confederates and the Royalists in 1643, this allowed
Ormonde to send 8,000 troops from Dublin and Munster and aid the King. Although most were in fact Englishmen, a small contingent consisted of Irish Royalists. In the instances where these Irish were captured, execution swiftly followed. After the Parliamentarians' capture of
Shrewsbury, a number of Irish soldiers were hanged in accordance with the law. In response,
Prince Rupert executed an equal number of Parliamentarian troops, much to the English Parliament's disgust. Similarly, after the fall of
Conwy Castle, seventy-five Irish prisoners were executed. One example of the severity of this law was the massacre of some Welsh civilian camp followers (who were mistaken for Irish) by Parliamentarian soldiers after the
Battle of Naseby in 1645. The Welsh, mostly women, were speaking the
Welsh language, which the Roundhead troops mistook for
Irish. Historian Charles Carlton has commented that the incident "was so unusual that it caused considerable comment". Irish military historian Pádraig Lenihan explains that, in practice, although the war at sea was covered by the Ordinance, as the Irish privateers captured more English sailors than the English did Irish and held English prisoners to exchange them for Irish prisoners, the ordinance for naval warfare lapsed. As he explains, "The 'laws' of war evolved like any primitive legal code, from the principle of reciprocity; self-interest counselled against brutality if there was the chance of being paid back in the same coin". ==Reciprocity in the Wars of the Three Kingdoms==