This essay as part of the Nimble Books series The Decisive Battles of the 21st century describes the battles carried out in August 2008 around South Ossetia and Abkhazia, after Georgia unleashed an attack upon them. The foreword is by a renowned professor of Geopolitics of the Hellenic Military Academy, Dr Constantinos Grivas. The Russians fought on the side of the breakaway Republics of Abkhazia and South Ossetia in a war, which is also known as The Five Day War . There is an extensive analysis on the diplomatic prelude occurring prior to the beginning of the hostilities, debating the causes that led Georgia to attack the breakaways and Russia to defend them. The prelude covers deep historical topics since the fall of the Soviet Union and the subsequent rise of Gamsakhurdia, the nationalist Georgian leader, Eduard Shevardnadze, whose toppling by the Rose Revolution brought Mikhail Saakashvili to power. Military operations are described and analyzed thoroughly starting from the skirmishes between Georgians and Ossetians and culminating with the war’s most decisive battle, the battle of Tskhinvali. The essay sheds light on the new Russian military doctrine and the reforms, which took place in the Russian Army, following the Five Day War, in all sectors including the Army, VDV troops, the Air Force and the Navy. Finally, an extensive analysis is carried out both in the framework of geoeconomics and that of international relations and geopolitics, around Russia’s future diplomatic ties with the EU and the US, separately, including the recent events in the US and European Economies, which have led to the manifestation of a European power centralized around Germany. The battle of Tskhinvali may well have settled the fate of the Caucasus for the 21st century, and foreshadowed the campaigns in Crimea, Ukraine, and beyond.