Carl von Clausewitz wrote that ‘the outcome of a major battle has a greater psychological effect on the loser than on the winner’. He wrote from experience: he was himself captured at the Battle of Jena by Napoleon’s forces in 1806, a battle very influential in the minds of the Prussians. This and cultural memories of defeats of the Napoleonic period likely inspired Prussia’s decision to parade in Paris following the French defeat in 1871.

After the Franco-Prussian war, France was humiliated by Germany’s unification ceremony in Versailles and the loss of Alsace-Lorraine. The country plunged into turmoil: the Paris Commune rose in revolt, Algeria saw rebellion, and Napoleon III was deposed after his capture at Sedan. France accepted a five-billion-franc indemnity — expected to cripple its economy for decades — and the new Republic itself seemed precarious, overshadowed by a Royalist-dominated Parliament.

But the Third Republic lasted for another 70 years: the longest constitutional streak since the end of the ‘old regime’. It survived the Dreyfus Affair, the Boulanger crisis, the economic crisis of 1888, and ultimately the Great War – a French triumph over its German rival.

Changes had not only been applied to the military. Paris undertook an ambitious programme with a ‘whole-of-society’ approach. The military, the country’s economy, and even its diplomatic corps would all be transformed to ensure France remained a great power and ultimately vaincre la défaite.

Writing from the vantage point of the mid-20th century, Charles de Gaulle observed that the then ‘laws on recruitment, organisation, and structure would set the foundations of the army until the Great War.’ After 1870, the causes of the defeat were assigned to a lack of reserves, outdated military thinking, and unready military equipment.

France undertook important reforms for military recruitment. Inspired by the recently victorious German Landwehr, the army introduced a five-year compulsory military service to develop a large number of active reserves. It was further improved in the 1890s to compensate for France’s demographic decline compared to its larger neighbour, and afterwards universalised to all male citizens for a 3-year compulsory service. The structure of the army was also revamped, connecting the corps more closely to local recruitment networks. Commanders, then, had a lot of influence in both peace and wartime. While this ‘regionalised’ the defence of the country, the command of the armed forces was also modernised and eventually centralised into a military staff in the 1890s.

In practice, this meant that after the 1870 defeat France abandoned an old approach rooted in Napoleonic orthodoxy in favour of a fully defensive strategy. Its entire military ‘hardware’ was replaced. New fortifications rose along France’s northeast borders, and the army adopted the bolt action rifle (the Lebel Model 1886) and the 155mm heavy artillery – innovations integral to France’s defence in the First World War.

Throughout the country, infrastructure was also modernised and expanded, for two reasons. First, in order to fully industrialise to better compete with its European neighbours in the economic sphere, and second, to better ready and mobilise forces in a possible conflict. Railways accomplished both objectives, and helped to promote the new Republican regime across all regions of France. As part of the Freycinet plan of 1879, this investment represented roughly a tenth of French GDP and was undertaken right up to 1914.

Rearming, financing new infrastructure, and paying an indemnity to Prussia equivalent to 15 per cent of its entire GDP sounds financially impossible. However, France refinanced the indemnity through perpetual bonds, or rentes, and launched the largest bond offering in its history, prompting investors to sell most of their foreign securities. Payments in British bills even contributed to higher interest rates set by the Bank of England and may have helped trigger the Long Depression that struck the British economy. Still, this protected the population’s living standards from inflation or a currency devaluation. Supported by an established banking sector and strong commercial surpluses, Paris successfully completed its indemnity in 1873 and preserved its creditworthiness. Interest payments on its national debt, however, became the largest portion of government spending, forcing tax reform that accompanied France’s transition from an Empire ‘of nobles’ to a democratic republic.

France emerged from the war in a state of diplomatic isolation. The newly formed German Empire created the League of the Three Emperors with Austria-Hungary and Russia and drew Italy into its orbit by 1874. Through Bismarck’s diplomacy, Berlin, instead of Paris, became Europe’s diplomatic capital and the German Chancellor helped inflame Franco-British antagonism over colonial disputes.

The shift from French isolation to German isolation on the eve of the First World War stemmed from two key developments. First, Kaiser William II’s rule constituted a radical break with Bismarck’s foreign policy. He allowed the trilateral partnership with Russia to unravel over tensions arising from the collapsing Ottoman Empire. And while he also sought a new entente with France, the Kaiser entered the African colonial race, creating new frictions with Britain, losing Berlin’s status of ‘honest broker’ in European disputes. In the meantime, Paris rebuilt diplomatic relations with Britain, its traditional rival, and deepened ties with Russia despite profound ideological differences with Saint Petersburg’s Tsarist regime.

Second, France reined in internal militaristic pressure to avenge its defeat – which almost culminated in a war in 1887 – and instead welcomed rapprochement and reconciliation when Germany eventually changed course. Contrary to common belief today, the main French political parties at the time strongly downplayed the loss of Alsace-Lorraine until the turn of the century, and only allowed it to resurface when France was in a stronger position prior to the First World War.

Against the odds, France would stand ready for the First World War in 1914, ready for its revanche. Several lessons endure today: reconciliation after defeat, the potential value of cultivating a ‘siege’ mentality, and the importance of mobilising national resources to rearm. Though France’s return to the international scene owed much to both its prestige and its status as a colonial power, both of these in turn relied on important internal reforms. This episode stands as an often-overlooked story of a triumph born from defeat.