First on the list is Albania, the most Muslim country in Europe, other than Turkey Obviously. Not much is known about the Albanian flag during 1914 but most say that this was the flag that they used. 

The flag of Austria-Hungary is complicated. The reason of this is because the flag that most people use is not its actually flag but its naval ship flag. Austria-Hungary has two flags, the Austrian yellow and black flag and the Hungarian red, white and green flag.

Belgum's flag follows the tricolor flag design that most of Europe uses. it was created in 1831 after they gained their independence from the Dutch. Even though Belgium got occupied during both World Wars it still survived. 

UH OH! it's the British Empire also known as Empire on which the sun never sets. It got that name from being the biggest country in all of history. And it even kept its flag the same though all of history. Most people say it's one of if not the best flag of Europe and I can see why the Union Jack (thats the name of the flag) is so popular. 

Bulgaria in 1914 is relatively a new country.  after winning the First Balkan War and losing the second one I have no Idea if they can win a world war. Bulgaria in history is known for picking the wrong side of a war as an example World War One and Two.

This is the oldest flag in the world, and no one knows where this flag came from. It's said to have flown from heaven and to be honest it is an amazing flag that set the basis for flags in Scandinavia. 

Interestingly this is the 2nd French Colonial Empire meaning there was a first. The first one was mainly destroyed after the French lost the 7 Years War. Then there was the revolution that gave France this flag that it still uses today with a different shade of blue and red.

This is probably what everyone is here for, The German Empire! It was created after Prussia won against France during the Prussian-Franco War. The German Empire was a formidable foe with a strong army that could have taken down France and Russia both if Brittian didn't join the War.

This flag was used during most of Greece's time as a country in the Modern Era. It was adopted in 1863 and was last in use in 1973, that's 110 years of the flag. It's based off the old Byzantine flag with the white cross design 

Just like The German Empire, The Italian Empire was a country that was unified do to nationalism. Like Prussia, Piedmont-Sardinia was the country that unified Italy under one government. The Italian flag now is based off this flag with the coat of arms removed.  

As you can see the flag of Montenegro is different than what it is today. It uses the Slavic tricolor flag that Serbia also uses to this day. They the tricolor it because Montenegro is a Slavic country that then was a part of Yugoslavia.

Norway's flag is based off of Denmark's flag just like the rest of Scandinavia. Denmark owned Norway for four centuries which is around 400 years. At least this flag is a little more detailed than Sweden and Finland.

Now here is an original. The Netherlands flag was the first tricolor flag in Europe, it seems everyone else copied them starting with the French. The Dutch has been using a tricolor flag for years starting with their flag in the 1570 that was the basis of tricolor flags in Europe

This is not the flag most people think of when talking about the Portuguese Empire, but the empire actually lasted until 1999. Portugal's flag uses its coat of arms that it has had since the 12th century or around 900 years ago.

Chad? No that's not the country of Chad, but it's the Romanian flag. The reason why the two flags are the same is because when Chad got its independence, Romania had a different flag because it was communist. After communism, Romania returned to its old flag.

It's the giant Russian Empire. The empire fell because of its treatment towards its people and how the last leader of The Russian Empire was not the smartest man at all. Followed by World War One and being destroyed by the Germans caused so many people to hate the empire that they were living in a revolted. 

Serbia has the same tricolor flag in the background just like Montenegro due to Serbia also being a Slavic nation. It flag looks similar to how it looks today but just with a difrent coat of arms on it

Spain used to be one of, if not the most powerful empire in the world. After the Napoleonic Wars it started to decline massively. This flag would never be used again after the Spanish Civil, but its modern-day flag is similar. 

Another flag that uses the Danish Cross and it's not as detailed as Norway's flag. Sweden has been using a variation of this flag thought out its existence and this is Sweden's modern-day flag.

The flag of Switzerland is famously known for having a square flag unlike the rest of the European countries. It's also famous for being neutral in almost every war since the modern-day inculdeing both World Wars.