The Ottoman garrison was composed largely of Albanian and Egyptian soldiers, a force of 12,000 men, commanded by Musa Pasha. A second Ottoman army of around 40,000 to 45,000 under
Omar Pasha Ottoman Commander-in-Chief, remained stationed at Şumnu (now
Shumen). The defenders were assisted by approximately six British officers, including Robert Cannon (Behram Pasha), Captain James Butler, and Lieutenant Charles Nasmyth. Both Butler and Nasmyth, officers of the Ceylon Rifles and veterans of the
East India Company army, arrived before the siege began and volunteered their services to the garrison. Another British officer present was Thomas Simmons, who served as the British commissioner attached to the Ottoman army. Prussian Colonel Grach, a former army engineer and specialist in entrenchments, also served on the Ottoman staff, advising on measures to strengthen the fortress's defences. Contemporary accounts emphasised the influence of these foreign officers. Captain Butler in particular left a detailed journal of the siege, describing daily skirmishes and expressing concern that the Ottoman troops had no regular routine for alarms and showed weak discipline. Historian James J. Reid argues that Butler's testimony reflected long-standing structural problems in Ottoman military practice, particularly the unreliability of sentry duty, which had been observed in earlier campaigns and would persist into the
Russo–Turkish War of 1877. The Russian vanguard reached Silistria on 5 April. General Karl Schilder, who had taken the fortress in 1829, resumed command, this time accompanied by Lieutenant-Colonel
Eduard Totleben, responsible for siege works and fortification. Although initial Russian plans envisioned a swift encirclement, they failed to completely isolate the town, allowing Ottoman forces to continue resupply operations. On 22 April, Field Marshal Prince
Ivan Paskevich assumed command of the Danube campaign and arrived from
Warsaw to Bucharest. Although entrusted with overall authority, Paskevich remained sceptical of the campaign's prospects, later urging a withdrawal in view of mounting pressure from Austria and signs of Allied mobilisation. By May the numbers of defenders rose to 18,000 after reinforcements arrived, while the Russian forces reached 90,000. On 28 May, the Ottoman garrison launched a sally against Russian lines, prompting a counter-assault on Arab Tabia, a key southern redoubt in the Silistra fortress complex. Russian forces briefly captured the position but, lacking reinforcements, were forced to withdraw after suffering heavy casualties. General Selvan was killed during the fighting. Russian casualties included 22 officers and more than 900 enlisted men killed or wounded. Ottoman reports recorded 68 dead and 121 wounded. On 2 June, Musa Pasha was struck by shrapnel and fatally wounded while preparing for prayers.; British officers Butler and Nasmyth temporarily assumed leadership of the garrison. Butler died after being shot in the head, Nasmyth took command and started re-organise the defence. In reports to
Nicholas I, Paskevich credited the defenders' tenacity to the strategic input of foreign officers. On 10 June, Paskevich reported being shaken by a nearby shell burst, after which he retired to Warsaw, officially due to health reasons. Command passed to General Gorchakov. Three days later, Schilder was severely wounded and died shortly afterward. On 20 June, Arab Tabia was recaptured by Russian forces. On 21 June, final preparations were underway for an all-out assault on the main fortress, scheduled for 4 am Yet only hours before the operation, Gorchakov received orders, originating from Paskevich on 13 June and endorsed by the Tsar, to abandon the siege: The sudden withdrawal was triggered by multiple strategic concerns: Austria had signed a convention with the Ottomans on 14 June granting it rights to occupy the Danubian Principalities, while Allied forces were now massing at
Varna, with 50,000 French and 20,000 British troops in theatre. On 24 June, the Russian army withdrew across the Danube, dismantling the pontoon bridge behind them. The Ottomans did not pursue. Russian losses during the siege are estimated at 2,500 dead and 1,783 wounded. == Aftermath ==