The war of 1870 between France and Prussia had two major consequences. First and foremost, the defeat of France and the subsequent Treaty of Frankfurt marked the end of the French dominance in continental Europe. Secondly, the German annexation of Alsace and Lorraine completed the establishment of German Empire which propelled them among the ranks of major European powers. The reunification of Germany caused a fundamental shift in the distribution of power in 19th century Europe. Bismarck had understood that among others his objective was to gain trust and make Germany look peaceful and friendly to other countries. Bismarck was able to convince other European powers that unified German empire was a status quo power and posed no security threats to them. Consequently, through his diplomatic tact and proactiveness Bismarck maintained peace in Europe for nearly two decades. The main theme of this article is to elucidate how the foreign policy undertaking by Bismarck and his system of alliance with Austria and Russia was able to prevent Germany from war against other European powers and thus preserved peace in Europe.
Bismarck and His System of Alliances
Aftermath the Franco Prussian War, France was in agony over the lost territories. The French despised the Germans, the hatred and the animosity against Germany was at all time high and the French would pounce upon any opportunity to get revenge on Germany. Bismarck, cautious of the French revanchism, directed his foreign policy and diplomatic engagement towards keeping France at bay and isolated, for he knew any hostile alliance by France with other European powers posed the danger of a potential two-front war that threatened the survival of the German Empire.So, he sought maintaining amiable relations with other countries and core part of his focus was on building a peaceful and friendly alliance with Austria and Russia. 
Initially, Bismarck found himself in a crossroad when Russia and Austria were contending over the issue of the Balkans. The relative decline of the Turkish power had opened up opportunities for Russia and Austria to fill the power vacuum in the region. The Balkans were of a strategic importance to both the Russians and the Austrians. With neither willing to let the other have influence in the region, Bismarck sensed Germany could become reluctantly involved in any future Austro-Russian conflict over the area. So, he proposed the formation of the League of the Three Emperors (Dreikaiserbund) which officially took shape in 1873. The objectives of the Dreikaiserbund were twofold: first and foremost, to ease off tensions between Austria and Russia over territorial claims in the Balkans and secondly, to prevent intervention in any potential strife between Germany and France. Although, the alliance did not have military component to it, for the time being, it fulfilled Bismarck’s aim to isolate France. In addition, the three parties also vowed to preserve the status quo in Europe.
Likewise, the German Empire had just come into being, although unified Germany was powerful, they weren’t indispensable and Bismarck knew this to the core. Back then, Britain controlled most of the world’s colonies as well as the oceans. In order to perpetuate Germany’s security and survival, the last thing Bismarck wanted was to antagonize Britain by getting himself into colonial competition. In addition, he viewed colonies as counterproductive that could easily create entanglements that result in diplomatic rift and disputes with powerful forces. Moreover, he sensed inherent danger of colonial commitments leading to shift German focus from Europe. Furthermore, Bismarck saw German future in Europe; his reference to “My Map of Africa lies in Europe” being a testament to it. This explains why, initially, in spite of domestic pressure, Bismarck was reluctant to get into colonial adventures for fears of confrontation with Britain and instead focused on trade and industrialization to bolster German economy.
The events in the Balkan Crisis (1875-1878) exacerbated Austria-Russia rivalry. Yet again, Bismarck feared Austro-Russian war could engulf the whole region. In order to prevent this from happening, Bismarck hosted the Congress of Berlin as an “honest-broker”. Dissatisfied with the outcome of the Congress and at Bismarck’s role, Russia ended the Dreikaiserbund. However, Bismarck was able to uphold and maintain the peace but at Russian antagonism. Fearing Russian military preparedness, Bismarck sensed Germany could be subject of a two-front war; realizing the need for ally, he got into military alliance with the Austrian empire and formed the Dual Alliance. The terms of the treaty stated both Austria and Germany would aid one another in the event of an attack from Russia. Later, Italy joined the alliance to make it the Triple Alliance. All these efforts from Bismarck made sure France formed no alliance with major powers.
With German alliance getting stronger, and feeling increasingly isolated, Russia came to an understanding with Germany and Austria which resulted in the Renewal of the Dreikaiserbund. This alliance effectively made sure France remained isolated and any French-Russian coalition wouldn’t materialize throughout his tenure. Once, on the verge of getting in a potential Austro-Russian conflict, Bismarck made sure, all contending parties were pacified and the status quo was preserved. However, the Bulgarian Crisis (1885) escalated the situation when Russia sought war with Austria and Britain would support Austria to stop Russian takeover of Bulgaria;the tension all but ended the Dreikaiserbund once again. The onus was on Bismarck to reconcile Russia and Austria and with his diplomatic adeptness Bismarck negotiated a defensive alliance – Reinsurance Treaty with Russia. The terms of the treaty secured neutrality in the event either party was attacked. It achieved one of Bismarck’s primary foreign policy goals –isolation of France.
However, all wasn’t gold for Bismarck in his foreign policy. The War in Sight Crisis of 1875 was one of such. France had recovered earlier from the defeats of the Franco-Prussian war than Germany anticipated them to and kicked off their rearmament program. By virtue of Security-Dilemma, Germany felt threatened. This unwanted crisis unfolded when an article “Krieg-in-Sicht” was published in Germany that mentioned several high-profile German officials contemplating preventive war against France. It created fear among the Europe’s elite; the Brits and the Russians made their position clear to Germany that no preventive war would be entertained. This unwanted incident resulted in Bismarck’s diplomatic failure and taught him a lesson that unallied France can still pose a threat. However, this incident can be considered a wakeup call for him who later initiated policies that sought peace in Europe and quite remarkably achieved it.
David Copeland’s Dynamic Differential Theory
Going by the realist assumption in a world characterized by anarchy and self-help where states are rational unitary actors, David Copeland in the Origins of Major war has posited that a dominant but a declining state perceives a rising power as a serious security threat and in order to perpetuate its survival, the declining major power is more than likely to resort to war. Thereby increasing chances of great power wars. By virtue of Dynamic Differentials theory, Copeland has maintained that polarity constraints the likelihood of war. In a multipolar world, a declining major power is only likely to pursue war as long as its relative military power is considerably higher than other major powers in the multipolar system. However, in a bipolar world, there is a clear delineation of friend and foes. There is also no third power that could take opportunity of the spoils between two major powers. Therefore, in this system, a declining power is likely to pursue war even if it just matches relative military capabilities of the rising power. 
It can be argued that during the time Bismarck was in power there were no major wars. However, it wasn’t because of his “love for peace” – as was demonstrated by Bismarck’s appetite for wars between 1864 and 1870 (with Austria, Denmark and France). Rather it had got to do with systemic conditions – polarity – constraining the prospects of war. Back then, Europe was multipolar. Germany was going through extensive industrialization and nowhere near did they possess a considerable military prowess. Bismarck knew any expansionist adventure would be met by force from Russia, France and Britain. Similarly, upon unification, Germany although became a powerful force, it was still only a rising power and the hegemon – Britain- was not in decline. Thus, war wasn’t initiated due to power differentials in economic and military aspects between the Hegemon and the rising power. Furthermore, talks of preventive wars were discussed in 1875, 1877 and 1887, however weren’t pursued for the very reasons.  Bismarck wanted peace and economic stability for the unified Germany until it became preponderant to challenge the system.
To sum up, Bismarck’s success in maintaining peace in Europe for nearly two decades can be attributed to his understanding of the constraints posed by the European multipolar order. Most importantly, his diplomatic engagements to pacify Austria and Russia as well as his ability to bring these two powers into defensive alliance with Germany made sure France remained isolated. It prevented Germany from facing two-front war which in turn prevented the breakout of a major war in Europe.
 Watson, Adam. The Evolution of International Society. (London: Routledge, 1993), 242-249
 Miller, Stuart T. “Bismarck and International Relations 1871–90.” Mastering Modern European History, 1988, 242–53. https://doi.org/10.1007/978-1-349-19580-0_16.
 Williamson, D. G. War and Peace: International Relations, 1890-1941. (London: Hodder Education, 2015)
 Copeland, Dale C. The Origins of Major War. (Ithaca: Cornell University Press, 2000), 15
 Ibid, 61