The Castle of Piombino remained a Pisan possession until Gerardo Appiani, after ceding Pisa to the Milanese Visconti, carved out an independent lordship centred on Piombino that included the islands of the Tuscan Archipelago: Elba, Pianosa, Montecristo, Capraia, Gorgona, and Giglio, for his family, who held the state intermittently until 1634.

In 1557, a peace treaty reinstated the Appiani as rulers of Piombino, with the exception of Portoferraio, which was given to the Grand Duchy of Tuscany, and the area of Orbetello, which became part of the State of the Presidi under Spanish control.

During World War II, in the days that followed the announcement of the Armistice of Cassibile, Piombino was the setting for one of the first episodes of the Italian resistance.

[4] On 10 September 1943, during Operation Achse, a small German flotilla, commanded by Kapitänleutnant Karl-Wolf Albrand, tried to enter the harbour of Piombino but was denied access by the port authorities.

[4][5][6] Once they entered and landed, the German forces showed a hostile behaviour, and it became clear that their intent was to occupy the town; the local population asked for a resolved reaction by the Italian forces, threatening an insurrection, but the senior Italian commander, general Fortunato Perni, instead ordered his tanks to open fire on the civilians, to disperse the crowds; De Vecchi forbade any action against the Germans.

[4][5][6] This however did not stop the protests; some junior officers, acting on their own initiative and against the orders (Perni and De Vecchi even tried to dismiss them for this), assumed command and started distributing weapons to the population, and civilian volunteers joined the Italian sailors and soldiers in the defense.

[4][5][7] Battle broke out at 21:15 on 10 September, between the German landing forces (who aimed to occupy the town centre) and the Italian coastal batteries, tanks, and civilian population.

[4][5][6] Many of the sailors, soldiers and citizens who had fought in the battle of Piombino retreated to the surrounding woods and formed the first partisan formations in the area.

East of Piombino, there was a power station with 1280 MW generation capacity with two chimneys, each 195 metres (640 ft) tall, but this is now being dismantled.