Tunnel warfare
Special boring instruments of complex design were developed.
In the Siege of Sevastopol (1854–1855) underground fighting became immense. At first the allies began digging saps without any precautions. After a series of explosions caused by counter mine action the allies increased the depth of the tunnels but began to meet rocky ground and the underground war had to return to higher levels. During the siege Russian sappers dug 6.8 kilometres (4.2 mi) of saps and counter mines. During the same period the allies dug 1.3 kilometres (0.81 mi). The Russians expended 12 tons of gunpowder in the underground war while the allies used 64 tons. These figures show that the Russians tried to create a more extensive network of tunnels and carried out better targeted attacks with only minimal use of gunpowder. The allies used outdated fuses so that many charges failed to go off. Conditions in the tunnels were severe: wax candles often went out, sappers fainted due to stale air, ground water flooded tunnels and counter mines. The Russians repulsed the siege and started to dig tunnels under the allies fortifications. The Russian success in the underground war was recognised by the allies. The Times noted that the laurels for this kind of warfare must go to the Russians.

American Civil War: In 1864, during the Siege of Petersburg by the Union Army of the Potomac, a mine made of 3,600 kilograms (8,000 lb) of gunpowder was set off approximately 6 metres (20 ft) under Maj. Gen. Ambrose E. Burnside's IX Corps sector. The explosion blew a gap in the Confederate defenses of Petersburg, Virginia, creating a crater 52 metres (170 ft) long, 30 to 37 metres (100 to 120 ft) wide, and at least 9 metres (30 ft) deep. The combat was accordingly known as the Battle of the Crater. From this propitious beginning, everything deteriorated rapidly for the Union attackers. Unit after unit charged into and around the crater, where soldiers milled in confusion. The Confederates quickly recovered and launched several counterattacks led by Brig. Gen. William Mahone. The breach was sealed off, and Union forces were repulsed with severe casualties. The horror of this engagement was portrayed in the Charles Frazier novel, and subsequent Anthony Minghella movie, Cold Mountain.
During the Siege of Vicksburg, in 1863, Union troops led by General Ulysses S. Grant tunnelled under the Confederate trenches and detonated a mine beneath the 3rd Louisiana Redan on June 25, 1863. The subsequent assault, led by General John A. Logan, gained a foothold in the Confederate trenches where the crater was formed, but the attackers were eventually forced to withdraw.

Modern warfare: The increased firepower that came with the use of smokeless powder, cordite and dynamite by the end of the 19th century made it very expensive to build above-ground fortifications that could withstand any attack. As a result, fortifications were covered with earth and eventually were built entirely underground to maximize protection. For the purpose of firing artillery and machine guns, emplacements had loopholes.

World War I: Mining saw a particular resurgence as a military tactic during the First World War, when army engineers attempted to break the stalemate of trench warfare by tunneling under no man's land and laying large quantities of explosives beneath the enemy's trenches. As in siege warfare, tunnel warfare was possible due to the static nature of the fighting.
On the Western and Italian Front during the First World War, the military employed specialist miners to dig tunnels.
On the Italian Front, the high peaks of the Dolomites range were an area of fierce mountain warfare and mining operations. In order to protect their soldiers from enemy fire and the hostile alpine environment, both Austro-Hungarian and Italian military engineers constructed fighting tunnels which offered a degree of cover and allowed better logistics support. In addition to building underground shelters and covered supply routes for their soldiers, both sides also attempted to break the stalemate of trench warfare by tunneling under no man's land and placing explosive charges beneath the enemy's positions. Their efforts in high mountain peaks such as Col di Lana, Lagazuoi and Marmolada were portrayed in fiction in Luis Trenker's Mountains on Fire film of 1931.
On the Western Front, the main objective of tunnel warfare was to place large quantities of explosives beneath enemy defensive positions. When it was detonated, the explosion would destroy that section of the trench. The infantry would then advance towards the enemy front-line hoping to take advantage of the confusion that followed the explosion of an underground mine. It could take as long as a year to dig a tunnel and place a mine. As well as digging their own tunnels, the military engineers had to listen out for enemy tunnellers. On occasions miners accidentally dug into the opposing side's tunnel and an underground fight took place. When an enemy's tunnel was found it was usually destroyed by placing an explosive charge inside.

During the height of the underground war on the Western Front in June 1916, British tunnellers fired 101 mines or camouflets, while German tunnellers fired 126 mines or camouflets. This amounts to a total of 227 mine explosions in one month – one detonation every three hours.  Large battles, like the Battle of the Somme in 1916 (see mines on the Somme) and the Battle of Vimy Ridge in 1917, were also supported by mine explosions.
Well known examples are the mines on the Italian Front laid by Austro-Hungarian and Italian miners, where the largest individual mine contained a charge of 50,000 kilograms (110,000 lb) of blasting gelatin, and the activities of the Tunnelling companies of the Royal Engineers on the Western Front. At the beginning of the Somme offensive, the British simultaneously detonated 19 mines of varying sizes beneath the German positions, including two mines that contained 18,000 kilograms (40,000 lb) of explosives.
In January 1917, General Plumer gave orders for over 20 mines to be placed under German lines at Messines. Over the next five months more than 8,000 m (26,000 ft) of tunnel were dug and 450–600 tons of explosive were placed in position. Simultaneous explosion of the mines took place at 3:10 a.m. on 7 June 1917. The blast killed an estimated 10,000 soldiers and was so loud it was heard in London. The near simultaneous explosions created 19 large craters and ranks among the largest non-nuclear explosions of all time. Two mines were not ignited in 1917 because they had been abandoned before the battle, and four were outside the area of the offensive. On 17 July 1955, a lightning strike set off one of these four latter mines. There were no human casualties, but one cow was killed. Another of the unused mines is believed to have been found in a location beneath a farmhouse, but no attempt has been made to remove it. The last mine fired by the British in World War I was near Givenchy on 10 August 1917, after which the tunnelling companies of the Royal Engineers concentrated on constructing deep dugouts for troop accommodation.
The largest single mines at Messines were at St Eloi, which was charged with 43,400 kilograms (95,600 lb) of ammonal, at Maedelstede Farm, which was charged with 43,000 kg (94,000 lb), and beneath German lines at Spanbroekmolen, which was charged with 41,000 kg (91,000 lb) of ammonal. The Spanbroekmolen mine created a crater that afterwards measured 130 metres (430 ft) from rim to rim. Now known as the Pool of Peace, it is large enough to house a 12 m (40 ft) deep lake.

Chaco War: On May 10, 1933, Paraguayan troops used a tunnel to attack in the rear of the Bolivian troops. They were victorious.

World War II: 

Sino-Japanese War: The term tunnel war or tunnel warfare (地道战) was first used for the guerrilla tactic employed by the Chinese in the Second Sino-Japanese War. The tunnel systems were fast and easy to construct and enabled a small force to successfully fight superior enemies. One particular tunnel network called the "Ranzhuang tunnel" evolved in the course of resisting Japanese counterinsurgency operations in Hebei. Particularly, the Chinese Communist forces or local peasant resistance used tunnel war tactics against the Japanese (and later the Kuomintang during Chinese Civil War). The tunnels were dug beneath the earth to cover the battlefield with numerous hidden gun holes to make a surprise attack. Entrances usually were hidden beneath a straw mat inside a house, or down a well. This allowed for flexible manoeuvers or exits.
The main disadvantage of tunnel war was that usually the Japanese could fill the holes or pour water in to suffocate the soldiers inside the tunnels. This proved to be a major problem but was later solved by installing filters that would consume the water and poisonous gases. It is said that there were even women and children who voluntarily fought in the tunnels.
The movie Tunnel War, which is based on the stories about fighting Japanese in tunnels, made tunnel warfare well known in China. More films were soon produced and adapted in the same setting.