did the former war mentioned earlier, really stretch for thirty years?
Yes, from 1618 to 1648.
Introduction
The Thirty Years' War was primarily fought in Central Europe between 1618 and 1648.
the mitochrondria is the powerhouse of the cell Yes. who was the first to discover it? Richard Altmann. what exactly is it? It is a semi autonomous double-membrane-bound organelle found in most eukaryotic organisms. who is the above-mentioned person? A German pathologist and histologist. when did he discover this organelle mentioned above? 1890. where is he from? Deutsch Eylau in the Province of Prussia. where is this province located? Kingdom of Prussia. who are the natives of this kingdom? UNANSWERABLE which year did it experience a plague? 1708. has it experienced any wars? Thirty Years' War, the Great Northern War and others. where was the latter war fought? Swedish Holstein-Gottorp, Swedish Livonia, and Swedish Ingria among others. when did it end? 1721. what was the reason behind the start of the war? The war began when an alliance of Denmark–Norway, Saxony and Russia, sensing an opportunity as Sweden was ruled by the young Charles XII, declared war on the Swedish Empire.
Yes, from  1618 to 1648. The Great Northern War took place between 1700–1721. Yes, between 1618 and 1648
Thirty Years' War Great Northern War Thirty Years' War
Introduction Introduction Introduction
The Thirty Years' War was primarily fought in Central Europe between 1618 and 1648. The Great Northern War (1700–1721) was a conflict in which a coalition led by the Tsardom of Russia successfully contested the supremacy of the Swedish Empire in Northern, Central and Eastern Europe. The initial leader The Thirty Years' War was primarily fought in Central Europe between 1618 and 1648. 
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Thirty Years' War [SEP] Introduction
The Thirty Years' War was primarily fought in Central Europe between 1618 and 1648. Estimates of the total number of military and civilian deaths which resulted range from 4.5 to 8 million, the vast majority from disease or starvation. In some areas of Germany, it has been suggested up to 60% of the population died. Until 1938, the war was usually presented as a German conflict; this changed when historian CV Wedgwood argued it formed part of a wider, ongoing European struggle, with the Habsburg-Bourbon conflict at its centre. This is now the generally accepted view, with related conflicts such as the 1568–1648 Eighty Years War, the 1635-59 Franco-Spanish War, and the 1629–31 War of the Mantuan Succession.