Question: Who failed to take back what the French believed instrumental in their defense?

full_context: Document 1: Crimean War: Soon after, a Russian cavalry movement was countered by the Heavy Brigade, who charged and fought hand-to-hand until the Russians retreated. This caused a more widespread Russian retreat, including a number of their artillery units. When the local commanders failed to take advantage of the retreat, Lord Raglan sent out orders to move up. The local commanders ignored the demands, leading to the British aide-de-camp personally delivering a quickly written and confusing order to attack the artillery. When the Earl of Cardigan questioned what they referred to, the aide-de-camp pointed to the first Russian battery he could see – the wrong one.
Document 2: Crimean War: In the north Eristov pushed southwest, fought two battles, forced the Turks back to Batum, retired behind the Cholok River and suspended action for the rest of the year (June). In the far south Wrangel pushed west, fought a battle and occupied Bayazit. In the center the main forces stood at Kars and Gyumri. Both slowly approached along the Kars-Gyumri road and faced each other, neither side choosing to fight (June–July). On 4 August Russian scouts saw a movement which they thought was the start of a withdrawal, the Russians advanced and the Turks attacked first. They were defeated, losing 8000 men to the Russian 3000. 10000 irregulars deserted to their villages. Both sides withdrew to their former positions. About this time the Persians made a semi-secret agreement to remain neutral in exchange for the cancellation of the indemnity from the previous war.
Document 3: Crimean War: Sevastopol fell after eleven months, and formerly neutral countries began to join the allied cause. Isolated and facing a bleak prospect of invasion from the west if the war continued, Russia sued for peace in March 1856. This was welcomed by France and the UK, where the citizens began to turn against their governments as the war dragged on. The war was officially ended by the Treaty of Paris, signed on 30 March 1856. Russia lost the war, and was forbidden from hosting warships in the Black Sea. The Ottoman vassal states of Wallachia and Moldavia became largely independent. Christians were granted a degree of official equality, and the Orthodox church regained control of the Christian churches in dispute.:415
Document 4: Crimean War: The Allied army relocated without problems to the south and the heavy artillery was brought ashore with batteries and connecting trenches built so that by 10 October some batteries were ready and by 17 October—when the bombardment commenced—126 guns were firing, 53 of them French.:430 The fleet at the same time engaged the shore batteries. The British bombardment worked better than the French, who had smaller caliber guns. The fleet suffered high casualties during the day. The British wanted to attack that afternoon, but the French wanted to defer the attack. A postponement was agreed, but on the next day the French were still not ready. By 19 October the Russians had transferred some heavy guns to the southern defenses and outgunned the allies.:431
Document 5: Crimean War: Minor naval skirmishes also occurred in the Far East, where at Petropavlovsk on the Kamchatka Peninsula a British and French Allied squadron including HMS Pique under Rear Admiral David Price and a French force under Counter-Admiral Auguste Febvrier Despointes besieged a smaller Russian force under Rear Admiral Yevfimy Putyatin. In September 1854, an Allied landing force was beaten back with heavy casualties, and the Allies withdrew. The Russians escaped under the cover of snow in early 1855 after Allied reinforcements arrived in the region.
Document 6: Battle of Balaclava: The Battle of Balaclava, fought on 25 October 1854 during the Crimean War, was part of Siege of Sevastopol (1854–55) to capture the port and fortress of Sevastopol, Russia's principal naval base on the Black Sea. The engagement followed the earlier Allied victory in September at the Battle of the Alma, where the Russian General Menshikov had positioned his army in an attempt to stop the Allies progressing south towards their strategic goal. Alma was the first major encounter fought in the Crimean Peninsula since the Allied landings at Kalamita Bay on 14 September, and was a clear battlefield success; but a tardy pursuit by the Allies failed to gain a decisive victory, allowing the Russians to regroup, recover and prepare their defence.
Document 7: Franco-Prussian War: On the French side, planning after the disaster at Wissembourg had become essential. General Le Bœuf, flushed with anger, was intent upon going on the offensive over the Saar and countering their loss. However, planning for the next encounter was more based upon the reality of unfolding events rather than emotion or pride, as Intendant General Wolff told him and his staff that supply beyond the Saar would be impossible. Therefore, the armies of France would take up a defensive position that would protect against every possible attack point, but also left the armies unable to support each other.
Document 8: Crimean War: Britain was concerned about Russian activity and Sir John Burgoyne senior advisor to Lord Aberdeen urged that the Dardanelles should be occupied and throw up works of sufficient strength to block any Russian move to capture Constantinople and gain access to the Mediterranean Sea. The Corps of Royal Engineers sent men to the Dardanelles while Burgoyne went to Paris, meeting the British Ambassador and the French Emperor. The Lord Cowley wrote on 8 February to Burgoyne "Your visit to Paris has produced a visible change in the Emperor's views, and he is making every preparation for a land expedition in case the last attempt at negotiation should break down.":411
Document 9: Crimean War: Winter, and a deteriorating supply situation on both sides of troops and materiel, led to a halt in ground operations. Sevastopol remained invested by the allies, while the allied armies were hemmed in by the Russian army in the interior. On 14 November a storm sank thirty allied transport ships including HMS Prince which was carrying a cargo of winter clothing.:435 The storm and heavy traffic caused the road from the coast to the troops to disintegrate into a quagmire, requiring engineers to devote most of their time to its repair including quarrying stone. A tramroad was ordered. It arrived in January with a civilian engineering crew, however it was March before it was sufficiently advanced to be of any appreciable value.:439 An Electrical telegraph was also ordered, but the frozen ground delayed its installation until March, when communications from the base port of Balaklava to the British HQ was established. The Pipe-and-cable-laying plough failed because of the hard frozen soil, but even so 21 miles of cable were laid.:449
Document 10: Crimean War: The Allies had had time to consider the problem. The French being brought around to agree that the key to the defence was the Malakoff.:441 Emphasis of the siege at Sevastopol shifted to the British left, against the fortifications on Malakoff hill.:339 In March, there was fighting by the French over a new fort being built by the Russians at Mamelon, located on a hill in front of the Malakoff. Several weeks of fighting saw little change in the front line, and the Mamelon remained in Russian hands.
Document 11: Crimean War: Frustrated by the wasted effort, and with demands for action from their citizens, the allied force decided to attack the center of Russian strength in the Black Sea at Sevastopol on the Crimean peninsula. After extended preparations, the forces landed on the peninsula in September 1854 and fought their way to a point south of Sevastopol after a series of successful battles. The Russians counterattacked on 25 October in what became the Battle of Balaclava and were repulsed, but at the cost of seriously depleting the British Army forces. A second counterattack, ordered personally by Nicholas, was defeated by Omar Pasha. The front settled into a siege and led to horrible conditions for troops on both sides. Smaller actions were carried out in the Baltic, the Caucasus, the White Sea and in the North Pacific.
Document 12: Crimean War: For months each side had been building forward rifle pits and defensive positions, which resulted in many skirmishes. Artillery fire aiming to gain superiority over the enemy guns.:450–462 September saw the final assault. On 5 September, another French bombardment (the sixth) was followed by an assault by the French Army on 8 September resulting in the capture of the Malakoff by the French, and following their failure to retake it, the collapse of the Russian defences. Meanwhile, the British captured the Great Redan, just south of the city of Sevastopol. The Russians retreated to the north, blowing up their magazines and the city fell on 9 September 1855 after a 337-day-long siege.:106
Document 13: Crimean War: France used the right moment and occupied Alger in 1830. In 1831 Muhammad Ali of Egypt, who was the most powerful vassal of the Ottoman Empire, claimed independence. Ottoman forces were defeated in a number of battles, and Egyptians were ready to capture Constantinople, which forced the sultan Mahmud II to seek for Russian military aid. 10 000 Russian army corps landed on the Bosphorus shores in 1833 and helped to prevent the capture of Constantinople, thus the possible disappearance of the Ottoman Empire was prevented.
Document 14: Crimean War: In August 1855 a Franco-British naval force captured and destroyed the Russian Bomarsund fortress on Åland Islands. In the same month, the Western Allied Baltic Fleet tried to destroy heavily defended Russian dockyards at Sveaborg outside Helsinki. More than 1000 enemy guns tested the strength of the fortress for two days. Despite the shelling, the sailors of the 120-gun ship Rossiya, led by Captain Viktor Poplonsky, defended the entrance to the harbor. The Allies fired over 20,000 shells but failed to defeat the Russian batteries. A massive new fleet of more than 350 gunboats and mortar vessels was prepared[by whom?], but before the attack was launched, the war ended.
Document 15: Crimean War: The landing was north of Sevastopol, so the Russians had arrayed their army in expectation of a direct attack. The allies advanced and on the morning of 20 September came up to the Alma river and the whole Russian army. The position was strong, but after three hours,:424 the frontal attack had driven the Russians out of their dug in positions with losses of 6000 men. The Battle of the Alma had 3,300 Allied losses. Failing to pursue the retreating forces was one of many strategic errors made during the war, and the Russians themselves noted that had they pressed south that day they would have easily captured Sevastopol.
ground_truth: the Russian defences
sub_queries: What did the French believe was instrumental in their defense? Answer: the Malakoff
Who failed to take back the Malakoff ? Answer: the Russian defences