The Gothic Line (German: Gotenstellung; Italian: Linea Gotica) was a German and Italian defensive line of the Italian Campaign of World War II. It formed Field Marshal Albert Kesselring's last major line of defence along the summits of the northern part of the Apennine Mountains during the fighting retreat of the Axis forces in Italy against the Allied Armies in Italy, commanded by General Sir Harold Alexander.

Adolf Hitler had concerns about the state of preparation of the Gothic Line: he feared the Allies would use amphibious landings to outflank its defences. To downgrade its importance in the eyes of both friend and foe, he ordered the name, with its historic connotations, changed, reasoning that if the Allies managed to break through they would not be able to use the more impressive name to magnify their victory claims. In response to this order, Kesselring renamed it the "Green Line" (Grüne Linie) in June 1944.

Using more than 15,000 slave labourers, the Germans created more than 2,000 well-fortified machine gun nests, casemates, bunkers, observation posts and artillery fighting positions to repel any attempt to breach the Gothic Line. By the end of August, the Tenth Army's sector, spanning from just north of Vicchio to Pesaro in the east, displayed a formidable array of defenses. It included 2,375 machine-gun posts, 479 positions for antitank guns, mortars, and assault guns, and 3,604 dugouts and shelters, among them 27 caves. Additionally, there were 16,006 riflemen’s positions, featuring embrasures made from fallen trees and branches. The Germans had also laid 72,517 Teller antitank mines and 23,172 S-mines, alongside 73 miles of wire obstacles and 9,780 yards of antitank ditches. However, only four Panzerturms had been completed, with 18 more under construction and seven others planned. Out of 46 smaller tank gun turrets intended to mount 1- and 2-centimetre guns, only 18 were operational. Furthermore, while 22 steel shelters were under construction, none had reached completion.

Initially, this line was breached during Operation Olive (also sometimes known as the Battle of Rimini), but Kesselring's forces were consistently able to retire in good order. This continued to be the case up to March 1945, with the Gothic Line being breached but with no decisive breakthrough; this would not take place until April 1945 during the final Allied offensive of the Italian Campaign.

Operation Olive has been described as the biggest battle of materials ever fought in Italy. Over 1,200,000 men participated in the battle. The battle took the form of a pincer manoeuvre, carried out by the British Eighth Army and the U.S. Fifth Army against the German 10th Army (10. Armee) and German 14th Army (14. Armee). Rimini, a city which had been hit by previous air raids, had 1,470,000 rounds fired against it by allied land forces. According to Lieutenant-General Oliver Leese, commander of the British Eighth Army: "The battle of Rimini was one of the hardest battles of Eighth Army. The fighting was comparable to El Alamein, Mareth, and the Gustav Line (Monte-Cassino)."

After the nearly concurrent breakthroughs at Cassino and Anzio in spring 1944, the 11 nations representing the Allies in Italy finally had a chance to trap the Germans in a pincer movement and to realize some of the British Prime Minister Winston Churchill's strategic goals for the long, costly campaign against the Axis "underbelly". This would have required the U.S. Fifth Army under Lieutenant General Mark W. Clark to commit most of his Anzio forces to the drive east from Cisterna, and to execute the envelopment envisioned in the original planning for the Anzio landing (i.e., flank the German 10th Army, and sever its northbound line of retreat from Cassino). Instead, fearing that the British Eighth Army, under Lieutenant-General Sir Oliver Leese, might beat him to the Italian capital of Rome, Clark diverted a large part of his Anzio force in that direction in an attempt to ensure that he and the Fifth Army would have the honour of liberating the city.

As a result, most of Generalfeldmarschall Albert Kesselring's forces slipped the noose and fell back north fighting delaying actions, notably in late June on the Trasimene Line (running from just south of Ancona on the east coast, past the southern shores of Lake Trasimeno near Perugia and on to the west coast south of Grosseto) and in July on the Arno Line (running from the west coast along the line of the Arno River and into the Apennine Mountains north of Arezzo). This gave time to consolidate the Gothic Line, a 10 miles (16 km) deep belt of fortifications extending from south of La Spezia (on the west coast) to the Foglia Valley, through the natural defensive wall of the Apennines (which ran unbroken nearly from coast to coast, 50 miles (80 km) deep and with high crests and peaks rising to 7,000 feet (2,100 m)), to the Adriatic Sea between Pesaro and Ravenna, on the east coast. The emplacements included numerous concrete-reinforced gun pits and trenches and 2,376 machine-gun nests with interlocking fire, 479 anti-tank, mortar and assault gun positions, 120,000 metres (130,000 yd) of barbed wire and many miles of anti-tank ditches. This last redoubt proved the Germans' determination to continue fighting.

Nevertheless, it was fortunate for the Allies that at this stage of the war the Italian partisan forces had become highly effective in disrupting the German preparations in the high mountains. On 2 April 1944, partisans belonging to the Eighth Garibaldi Brigade managed to occupy Sant'Agata Feltria; their ambush of a German detachment sent to round up partisans led to the Fragheto massacre on 7 April. By September 1944, German generals were no longer able to move freely in the area behind their main lines because of partisan activity. Generalleutnant Frido von Senger und Etterlin—commanding XIV Panzer Corps (XIV Panzerkorps)—later wrote that he had taken to travelling in a little Volkswagen "(displaying) no general's insignia of rank—no peaked cap, no gold or red flags...". One of his colleagues who ignored this caution—Wilhelm Crisolli (commanding the 20th Luftwaffe Field Division)—was caught and killed by partisans as he returned from a conference at corps headquarters.