Belle Époque ended up by World War I starting.
However, espresso remained popular in Italy.
Luigi Bezzera, Desiderio Pavoni, coffee machine developers and coffee roaster such as Luigi Lavazza kept promoting espresso, which remained popular around bars in nortern  industorial cities or large cities in the era in Italy.

In the early 1900s, Italian espresso machine innovators such as Pavoni began to introduce the machine and cafes began to appear all over Northern Italy.These bars began to supply espresso coffee.  

These bars purchased roasted coffee bean from roasters.
One of the  dominant roaster is Luigi Lavazza.

Luigi Lavazza was an Italian entrepreneur who founded the famous Lavazza coffee company that bears his name today.

Desiderio Pavoni was a pivotal figure in espresso history who transformed Luigi Bezzera's invention into a commercial success. 
Desiderio Pavoni purchased Luigi Bezzera's patent in 1903, recognizing the potential that Bezzera himself couldn't capitalize on due to lack of financial resources and marketing expertise. 
In 1905, Pavoni founded the La Pavoni company and began producing the espresso machine industrially, manufacturing one machine daily in a small workshop in Via Parini, Milan.

In Europe, the period from around 1889, when the Paris World's Fair, where the Eiffel Tower was unveiled, to the outbreak of World War I is known as the Belle Époque (Beautiful Era).
This was also a period when various technologies developed due to the Industrial Revolution and artistic movements such as Art Nouveau emerged.
During this time, Luigi Bezzera developed a new espresso machine in Italy.

How was Espresso Machine born pre war, which is perfected by Achille Gaggia right after WWII in Italy?
 Angelo Moriondo was a pioneering Italian inventor who created the world's first espresso machine in 1884. Here's his remarkable story:

Giovanni Achille Gaggia (1895–1961) was an Italian inventor who revolutionized espresso coffee. 
Working as a barista in his family's coffee bar, Caffè Achille, in Milan during the 1930s, he became dissatisfied with the bitter, burnt taste of coffee produced by the steam machines of that era .

After World War II、many Amecrian Soldiers spread Instant coffee like Nescafe、and it was included in Care packages delivered to civilian populations around in Western Europe, Japan right after WWII and so on.
But in Japn, instant coffee is not spread soon, because of limitation of import of coffee regulation.

After that, in the 1960s, when restrictions on imports of instant coffee were lifted in Japan, instant coffee became popular.

By the time the U.S. entered World War II in 1941, Nescafé was already in the emergency rations of every departing U.S. soldier , so the hundreds of thousands of American soldiers who occupied Japan from 1945-1952 would have been familiar with it and likely brought it with them.
However, coffee didn't immediately become popular in Japan. During World War II, the Japanese government established a ban on coffee imports that lasted until 1950 , which limited its availability during the early occupation period.

Nescafé's introduction significantly increased coffee consumption and created new coffee fans, particularly during and after World War II.
U.S. per capita coffee consumption actually peaked in 1946 at 46.4 gallons per person - right after the war when Nescafé had become widely popular. During World War II, Nescafé's sales volumes doubled, showing rapid growth in popularity.

Nestlé chemist Dr. Max Morgenthaler worked for seven years to develop a soluble instant coffee that would preserve coffee's natural flavor and aroma. 
The challenge was to create a product that could be easily prepared by simply adding water while maintaining the quality of real coffee.
On April 1, 1938, Nescafé was officially launched in Switzerland.