There are four reasons why the French will step in. The first is that President Sarkozy is a student of history. France got involved in two disastrous stalemates in the last century on the western front in World War I and in Indochina mid century. These twin debacles coupled with the fiasco of the French collapse in 1940 sucked the vitality out of French martial traditions. France cannot afford a long war of incremental escalation such as the American involvement in Vietnam, and his country’s earlier Indochina experience.
A second reason is that France clearly fears and cannot tolerate, another wave of Muslim immigration into a country already on the brink of seeing the Gallic race becoming a minority in their own homeland. Italy is even more vulnerable in France in this respect as she is Libya’s former colonial ruler and a likely destination of choice for refugees. That is why I believe that the Italians may assist in a ground intervention.
Third, Sarkozy clearly wants French world, or at least regional, leadership restored. He wants to succeed where De Gaulle failed, and the Libyan situation presents a golden opportunity to restore the martial traditions of the French glory days of the Sun King and Napoleon.
Finally, of the European powers, only France retains a credible power projection capability beyond continental Europe.