"...categorizing the Second Empire into three "periods" - Early Empire, High Empire, and Late Empire. The exact definition of Late Empire varies, usually but not always characterized by historians as beginning with either the death of Napoleon IV or the death of Georges Boulanger, but outside of a few figures who peg its arrival much earlier - sometimes as early as the Paris Bourse crisis of 1890 - it is generally agreed to have begun sometime in the first six years of the reign of Napoleon V and continued on through the ensuing decade, the Central European War, and the Second Empire's eventual overthrow.
Late Imperial France has been a subject of scholarly exploration for decades now as interest has risen in French politics of the period being downstream of French culture in that same period, as a potential avenue for exploring the causes of the Central European War. In part, this was thanks to the increasingly fragile political position of Raymond Poincare, and a great deal of early 20th century analysis has generally viewed Poincare's belligerency towards Germany and Italy, particularly as the internal situation in Austria-Hungary deteriorated 1918-19, as being a response to this. But why was Poincare's position so increasingly fragile?
The answer is in part that the France of the late 1910s was a deeply anxious country that increasingly lacked confidence in itself, either domestically or internationally, and that anxiety found belligerent nationalism as an outlet that could unite anticlerical liberals and radical socialists with monarchist conservatives towards an external enemy, a process that Poincare pursued with vigor. The reality is that France, despite being a world leader in aerial and automotive technology, was beginning to feel like it was drastically falling behind its peer nations, particularly after the Anglo-German Convention of 1916 that split Portuguese Africa in half, and this general sense of national malaise trickled down to - or perhaps was fueled by - the deep social divisions and anxieties of the country. Since the National Contract had been promulgated by Napoleon IV in 1878, the government of France had gone out of its way to attempt to marry the working classes, viewed as a better monarchist bulwark than the liberal bourgeoisie and urbane intelligentsia, to the Crown. Unlike most European states, the shadow of Revolution - be it 1789, 1830, or 1848 - hung over the Second Empire, and it was taken as fact by monarchist officialdom that the abortive Paris Commune of May 1868 had simply been a fourth edition of such upheavals strangled in its cradle. As such, republicanism was viewed as the enemy much more ardently at the Tuileries and as a much more live and real threat than elsewhere, and this anxiety colored both policy, such as France's generous welfare state that was grounded partly in Catholic social teaching, and politics, such as the near-panic from Prime Minister Poincare about his ill-advised decision to go to the polls in October of 1915 rather than six months later in which his Bloc Nationale lost her majority and was faced with insurgents of both Right and Left.
The specter of previous French upheavals was, of course, a hallmark of French politics (and perhaps even continues to be today), and by 1916-17 it could be credibly said that there was not one France, but rather two. There was the France of small medieval villages and rolling hills, of ancient vineyards and orchards, punctuated by church spires and associated with a rural, bucolic life. This was the France of Napoleon IV and Georges Boulanger, and the France with which the privately irreligious Raymond Poincare struggled to connect. Then there was the France of the cities, primarily embodied by Paris. Despite the conservatism of the French government, its capital had nonetheless retained its reputation as the City of Light, a place where artists, intellectuals, exiles and free-spirits gathered at cafes to debate philosophy, paintings, music or the emerging art form of cinema. Paris was a hotbed of radical, often republican, activity, and while Church attendance and religiosity across France itself was high (and growing, contravening trends elsewhere in Europe where it was flat to in slight decline), Paris was regarded as the epicenter of secularism, a political philosophy espoused in France as laicite.
Observers of French culture and politics, particularly from the polycentric United States, were often amazed at the vitality which Paris had in the French economic and political geography while also being stunned at how it seemed to exist in a different world than the conservative provincial France. Schools across most of the country, particularly in the south and east, were generally operated by the Church in partnership with the state and monastic orders; Paris, and to a lesser extent Lille and Marseilles, saw the bulk of their teaching done in private, secular academies as politicians who represented their interests, such as Aristide Briand of the Union of Socialist Reform, advocated for nationalizing these lycees and extending their purview to every student in France, a position which was met with considerable hostility from the devout majority.
It left France as a polarized country, split between its growing and cosmopolitan capital and satellite cities and traditionalist countryside, both claiming with some credibility to represent French interests abroad and at home as political and cultural practices were fairly homogenous depending on what side of the split one was on. However, one thing around which French society was not polarized was an intense French nationalism - for liberals, its legacy of revolution and reform, and for conservatives, its status as the chief defender of modernizing political Catholicism in Europe [1] - that was often directed externally. It was thus the case that most of the French public was equally contemptuous of Germany, Britain, Italy, even Spain, and with this being one of the few things that united a country that felt anxious about its place as the Great Power of the continent in Berlin's growing shadow, it was of course an itch that the French political class was ever-eager to scratch..."
- The Central European War
[1] Something I think is important to note about French Catholicism ITTL is that it takes pride in the National Contract and, due to having had to defend itself from secular and republican impulses over the 19th century in a way that, say, Habsburg Austria has not, but also not being actively sidelined by anticlerical forces as in Italy, has allowed it to both be more proactive in how it deals with the public and more sophisticated in its organization.