Born into the important Ghibelline family of the Antelminelli, Castruccio Castracani was driven out of Lucca and initially lived in exile in Pisa, then for a long time in England, where his skill in the use of arms earned him the favor of King Edward II of England.
However, a murder he committed forced him to move to France, where Philip the Fair was in need of "men at arms".
After a few years he returned to Italy, where he stayed in Verona and Venice.
Following the descent of Arrigo VII into Italy, after the signing of the Peace of Ripafratta, he joined the Ghibelline troops of Uguccione della Faggiuola, recognized leader of the Tuscan Ghibellines and lord of Arezzo and Pisa (1314), together with whom he participated in the taking and the subsequent sack of Lucca, ruled until then by the Guelph side.
He fought as commander of a part of the Ghibelline army and was the main architect of the victory over the Florentines. Historians recall the damage caused by Castruccio and his troops to the Florentine territory.
He fell from grace he was imprisoned awaiting execution. However, following a popular revolt in Lucca and Pisa, Castruccio was freed and acclaimed Captain General of the city of Lucca, and on 12 June 1316, Consul for life.
The Ghibelline power and the lordship of Lucca were consolidated in the following years by Castruccio Castracani.
In 1320, Castruccio suddenly resumed hostilities against the Florentines, breaking into their territory. In the same year the Archduke of Austria Frederick I of Habsburg appointed him vicar for Lucca, the Lunigiana and the Val di Nievole, and in this position he was confirmed in 1324 by the emperor Ludovico il Bavaro, his friend and ally.
On 22 September and 23 September 1325, in the battle of Altopascio, he again beat the Florentines on the Guelph side by making a large raid of prisoners, and for this too he was nominated, again by Ludovico il Bavaro, duke of Lucca.
Then he subjected Pistoia and consolidated its walls demolished by the Guelphs of Florence and Lucca in 1306.
While he was then moving towards Florence, he was forced to give up the siege to attend the coronation of Emperor Louis in Rome. During his stay in Rome, full of satisfactions, he too was appointed Grand Legate for Italy.
Later he developed a plan to flood Florence by closing the Arno at Lastra a Signa, in the locality of Gonfolina, which others deemed impossible.
Ludovico il Bavaro granted Castruccio Castracani for his merits to insert in his heraldic coat of arms («Can bianco in campo Azzurro»), the blue and silver chessmen of the Dukes of Bavaria.
Castruccio was excommunicated in 1327 by Pope John XXII, due to his aversion to the temporal power of the Church. Also in that year, he waged war in Liguria in support of the Ghibelline families Doria and Spinola, intending to take power in the Republic of Genoa. Advancing along the Riviera, he laid siege to Sestri Levante, before retreating towards the Lunigiana area.
According to the Anonymous from Pistoia, Castruccio's children were Giovanni, Arrigo and Valeriano as well as Altino, their bastard brother and their sister Dialta who married Filippo Tedici who, with Castruccio's complicity, took over the city of Pistoia.
He died in Lucca on September 3, 1328, due to a sudden malarial fever, while he was preparing to take up arms again against Florence.

Many places and works of the historical and monumental heritage of the Italian Middle Ages are linked to the name of Castruccio Castracani and are particularly interesting as regards the fortifications.
In Lucca he built the Augusta Fortress in 1322.
In Pietrasanta (Lucca) he restructured the fortified village and built solid walls connected to the Rocca di Sala around the city.
In Bagni di Lucca (Lucca) in 1317 he built a bridge on the place where in 1840 Lorenzo Nottolini built the Chain Bridge later called Ponte a Serraglio which owes its name to the fortified bridge built to defend the valley from Castruccio Castracani.
In Ghivizzano (Lucca), Castruccio Castracani restructured the entire fortress and built a palace, whose walls will host illustrious characters over the centuries.
In Castelnuovo Garfagnana (Lucca) the fortress, originally from the 11th century, was fortified by Castruccio Castracani. In Prato, Castruccio reinforces the fortifications of the castle of Carmignano.
In Serravalle Pistoiese (Pistoia), he completed the mighty fort and raised the mighty watchtower.
In Piteglio (Lucca) he built the stone bridge over the Lima stream, known as Ponte di Castruccio.
In Agliana (Pistoia), during the siege of Pistoia in 1325, he had the fortifications built.
In Avenza (Massa Carrara) perhaps Castruccio had the pre-existing fortifications enlarged, but it is certain that the so-called Castruccio tower dates back to the period of his presence and is due to him.
In Pontremoli (Massa Carrara), Piazza del Duomo and Piazza della Repubblica, formerly one and the same, are due to the division, intended to put an end to the disputes between Guelphs and Ghibellines, created through the curtain wall called the fortress of Cazzaguerra built in 1322.
In Sarzana (La Spezia); around 1320 he modified and strengthened the structure of the Fortress of Sarzanello and in 1324 he made numerous and significant changes to the defensive systems of the so-called Citadel or Fortress, located at the southern entrance to the city.
In Iolo (Prato) the road that connects the town to Pistoia is dedicated to him, called via Castruccio, a name given to the street because his troops stopped in the area during the invasion of the fourteenth century.
In Pistoia, in 1325, he had the Bella Spera fortress built, called Rolanda or Valeranda from the name of his son Valeriano. Today the imposing stone facade is visible.
In Lancisa (Pistoia), on the Pistoia Apennines, where for a period he took control of the fortification of Castel di Mura.
At Montopoli Val d'Arno (Pisa): tower and arch by Castruccio Castracani;
In Massa (Massa Carrara) he almost totally destroyed the Rocca Malaspina and then strengthened it.