What events and developments led to greater stability and more limited warfare within europe?

Developments: An increase in medical knowledge and medical specializations; by the mid 1800s specialties had become very popular in Europe, because of this, each organ had its own doctor and even its own special clinic. An important factor that led to this was a new approach of disease and a better perception of anatomy due to the practice of posthumous dissections. In this era the germ theory replaced the humoral theory of disease.

A development in better sanitation also helped Europe to obtain a greater stability. A lack of sanitation in European Dark Ages (5th- 15th century AD) demanded the medical and scientific communities to start fighting this dangerous health issue. During this period of time, towns across Europe were full of feces, dirty, had contaminated water and were extremely crowded. An expansion of epidemic diseases such as tuberculosis, cholera, smallpox and yellow fever caused a rapid reduction in the life expectation of Europeans. Modern age sanitation started in Europe between the 16th and the 19th century, and with it the developing of plumbing, latrines and personal toilets, as well as water purification techniques, transportation and creation of drinking water helped personal hygiene to be applied by everyone.

Events: There were several wars in Europe in the 18th century, European nations focused all their attention on the fight for power, dominance and territory. Wars emerged out frequently as monarchs tried to understand who was going to rule in the various areas of Europe. Internal relations in Europe during the 18th century were unstable and lead major European powers into extended wars. With the Treaty of Aix-la-Chapelle, in 1748, a diplomatic revolution negotiated and brought peace in Europe. In the meantime each nation continued to build their armies but at the end they were forced to pay attention to their interior.  

they wanted the u.s. to fight on the side of the central powers.