The answer of this question depends heavily on which nation's army you are referring to. As for the United States, the US declared war on Germany in 1917. The first forces to fight were the Navy and the Marines (so-called "Doughboys"). General John J. Pershing lead the American Expeditionary Forces (Army) into what little combat the US was involved in, in Europe.
The army of Russia was called the red army during world war two. and the leader of Russia at the time was their dictator Joseph Stalin
Lawrence Tyson led the 2nd Infantry Division of the United States Army during World War I.
General George S. Patton .
General Lee of virginia led the confederate army and General Grant led the union army
On September 1st 1939 the German army invaded neighboring Poland and caused what is known as today World War II.
On September 1st 1939 the German army invaded neighboring Poland and caused what is known as today World War II.
The leader of the Greek army was Agamemnon.
While its clear why Russia had to surrender in WW 1, it is necessary to note how large its army was in 1914, the war's beginning. In 1914, Russia led the world with a staggering army of 1,300,000 troops. France was second with 910,000.
Macarthur
George Washington was commander-in-chief of the Continental Army during the Revolutionary War against Britain.
England hasn't had its own army for 300 years. You probably mean the British Army.
Adolf Hitler