The Grimaldi's, one of the most influential Guelf families of Genova, were twice chased away from their city by the Ghibellines. In 1270, they retorted by seizing Ventimiglia, Menton and Roquebrune. After the insurrection of December 1270, the defeated Guelfs retreated to Provence, where Rainier Grimaldi, who was head of the family, began arming his fleet to retaliate.

On January 8, 1297, Francois Grimaldi took power of the Monaco fortress. In the book, "Monaco, its Origins and History", the indisputable authority on Monaco's history, author Gustave Saigne relates the details of this paramount turning point in the history of the Principality : "During the night of January 8, 1297, a monk appeared at the gates of Monaco. Inconspicuously, Francois Grimaldi was let through. Barely having entered the enclosed grounds, the imposture monk threw himself over the guards, apparently few were holding watch, and a full pledged attack was launched as the large Guelf troops, which had been hiding closely behind concealed by the obscurity of the night, forced the gates before the guards could react." 

By his actions, Francois Grimaldi forever engraved the family name on the flanks of Monaco's rock. Until that moment, its situation had remained precarious as events of the years preceding 1297 witnessed: 

- the political fall down of the Saintly Roman-Germanic Empire. 

- the internal disarray in many Italian cities fallen prey to the gutting wars between the rivaling Guelf and Ghibellines families. 

- the indecisiveness of Charles II of Anjou, Count of Provence. 

The rock belonged to Genova since 1215. To seize it was a clear act of war, but also a symbolic act with respect to the Ghibellines, who remained in power in their home land. 

Francois Grimaldi in monk frock, by fooling his adversaries and seizing the fortress, avoided a siege which would have been costly in terms of means and lives. Seizing the strategically located harbor and fort also gave him the best chances by which to reconquer Genova. The Grimaldi's and their partisans maintained their position on the rock for just over four years, during which time, they pursued a merciless chase of the Ghibellines fleets and trade ships sailing between Italy and the ports of Languedoc.

Throughout this period, Charles II of Anjou was digging himself deeper into an increasingly difficult situation facing the accentuating threats of the Aragons territorial claims. He needed support which he was hoping to receive from Genova, to reinforce his fleet of ships. 

Recognizing the value of the circumstances, Rainier Grimaldi deployed his naval forces and put his maneuvering talents into action. It was no longer a matter of fighting solely for his personal interests, but to offer his forces to serve a Prince who would one day know how to compensate him well. He did the same with the King of France, Philippe le Bel, for whom in 1304, he brought back the victorious naval conquest of Zeriksee against the Flemish fleet, honoring him the title of 'Admiral of France'. Rainier displayed unique comportment and model behavior, the tradition of which the Grimaldi's have continued : recognition as a force that a powerful neighbor will appreciate, and find in its own interest to take advantage of, under the reciprocated conditions of obtaining aid and protection, towards the common interest of political emancipation. 

Under the benevolent initiative taken by Charles II to return Monaco to Genova, the Grimaldi's conducted negotiations with perseverance and shrewdness commanding respect for their conditions. Past were the days of surrender and being treated as defeated, now transformed to the pursuit of discussions with regard for one another as equals. 

The restoration of Monaco to the heart of the Republic of Genova, which was for many at the time, considered a return to the former situation, although not considered so by the Grimaldi's. However, Rainier, leader of the dissidents, preferred to retreat to Provence, demonstrating his desire for independence. He was the historical instigator of Monegasque independence. 

Information supplied by the Monaco Centre de Presse
Pages by GALE FORCE of Monaco 
http://www.monaco.mc/monaco/700ans/grimaldi.html#orig