Fro what it looks like this is a few months into the war so using thay context I'll try to give an example of each country.

Russia: The Russian bear eating Austria Hungary With the cossack horde charging in. Russia early in the war were able to make massive gains against Austria Hungary basically crippling their whole empire and causing thousands of casualties. It wasn't until the Germans failed to win a decisive victory on the western front that they put massive amounts of resources into fighting the Russian empire thus saving Austria Hungary.

Austria Hungary: collapsing while desperately clutching Germany for support. Read Russia.

Germany: The mighty eagle striking the French while being pinned by the Russian bear. Early in the war Germany was hoping to win a decisive victory against the French by going through Belgium and Luxembourg. Despite early successes the French and British started to dig trenches thus began the race to the sea as each army tried to out manure each other.

France: Bravely facing the eagle while dressed in bright colors eager for battle. See Germany

Britain: Coming in from their isles not changing anything at home while their subjects come in from other parts of the world. You can also see the British fleet starting the north sea blockade. The north sea blockade was a idea put in place by Winston Churchill while he was lord of the admiralty. Instead of blockading Germany at her ports Britain would use their fleet to control the north sea thus cutting supplies from neutral countries.

Ottoman Empire: From what it looks like they are forcibly being dragged in the war by Germany however I don't know the context for that.

In addition to the sketch by Starmoses:

The Austrian (Austro-Hungarian) is dressed in the traditional costume of a 19th century clown.

The Brit is in the attire of a shopkeeper (vest, rolled up sleeves, bow-tie to avoid catching on things)... this is probably a play on the German dismissal of "England" as "nothing more than a nation of shopkeepers"... it's a clever reversal, as this "Business as Usual" is not shopkeeping but bringing the saber and boot to the Continent. (perhaps a very subtle allusion to the victory over Napoleon? not sure here.)

The other Brit soldiers are from India, Australia, and either Canada or South Africa--symbolizing Britain drawing on it's imperial manpower.

France is wearing the Liberty cap and overall dresses as "Marianne" (a traditional symbol of France).

Belgium is down but not out... which makes me think this is quite early?

The Netherlands has a bruised/bloody nose? Not sure about that...

Norway and Sweden (neutral) are watching like one watches a dramatic opera: Sweden has opera glasses, Norway is whispering in hushed tones...

The Italian is singing "You Made Me Love You"--a popular song by Al Jolson (an American minstrel singer) from the previous year, 1913.. I'm pretty sure this is a jab at Germany, in that Italy was part of the German-Austro-Hungarian "Triple Alliance", and was thereby supposed to join the Central (Germany-AH) powers in any conflict... but now is clearly having second thoughts. (Italy ultimately joined on the Entente side... i.e. with Britain-France-Russia.) So Italy singing the song is a joke about Italy feeling torn...

The little yap-yap dog is the Kingdom of Serbia, "worrying" (nipping at) Austria-Hungary... so this is probably referring to the (fruitless) attack across the Sava river in 1914...

Greece is bloodied--but ready to fight the Ottomans, referring to the Balkan War of 1912-23.

Same with Bulgaria. (this is before Bulgaria joined Germany and A-H, which occurred in 1915)

Romania is ready to fight Austria... not sure about the significance of the cannon.

The Ottoman (wearing a traditional Fez) is 'cut off' by the Royal Navy in the Adriatic and the Russian Navy in the Black Sea... the Prussian (Wilhelm in German army uniform) is "forcing" him to sit on a powderkeg... i.e. the cartoonist is saying this is a really bad idea for the Ottomans to enter the war, and are doing it only under duress.

Switzerland (neutral) has his fingers in his ears, wishing the whole thing would just go away.

Portugal is spoiling for a fight... (boxing).... probably symbolizing the tension between German and Portuguese colonial troops in southern Africa.

And Spain (neutral) is just chillin'... watching from afar.