Dublin with Rosen and left the forces before Derry under Maumont's command. However, Richard Hamilton also stayed and was of equal rank. Both had been promoted Lieutenant-General quite recently. Frictions sometimes arose between the Irish and the French officers about who was in command. On 21 April the besieged, led by Murray, sallied and killed Maumont. This has also been called the Battle of Pennyburn. Command devolved to Richard Hamilton. On 23 April Fort Culmore, which guarded the mouth of River Foyle, surrendered to the Jacobites. During another sally, on 25 April, the Duke of Berwick and Bernard Desjean, Baron de Pointis, were wounded and Pusignan killed. On 6 May Brigadier-General Ramsay attacked the Windmill Hill before the Bishops Gate and drove out the sentinels posted there by the besieged, but Baker knew the importance of this position and on the next day, the besieged sallied from the Ferryquay Gate and retook Windmill Hill. Ramsay was killed and other officers were taken prisoners. Among them were William Talbot, a nephew of the viceroy, Viscount Netterville and Gerald FitzGerald, Knight of Glin. Baker built a line of earthworks from the river up to Windmill Hill and back through the Bog to the river downstream of the town. On 7 May Williamite England formally declared war on France. This officially sanctioned what was already happening around Derry since 18 April. Two French generals, Maumont and Pusignan, had already been killed in the siege. France never declared war on England as they saw James as the rightful king and the Williamites as mere rebels. On 11 May a French fleet landed more equipment and troops at Bantry Bay in southwestern Ireland and fought the battle of Bantry Bay against an English fleet. The battle was inconclusive, but the French seemed to have had the advantage. On 30 May the besiegers received heavy guns and mortars. Before that date they only had field artillery. Matthew Plunkett, 7th Baron Louth, and de Pointis were in charge of the mortars, which were placed on the right bank of the river where no sally could reach them. The mortars fired almost 600 explosive shells into the town. About this time disease and hunger took hold within the city. It became evident that the town needed to be relieved. William gave that task to Major-General Percy Kirke, who decided to first explore the mouth of River Foyle to