What happened to deserters in world war one?

If found they were shot, hung or returned to the front.

they were executed usually by being shot at dawn ...

depends which army and when they did it

deserting in face of the enemy was death in all armies (i.e while they were attacking you - or you were attacking them)

deserting at other times could be death (esp if you threw away your weapon while you were deserting)

otherwise a hefty sentence in a military prison

Prison or death

That would depend on which army or navy they were serving in, and on which front, and on what continent, and on what kind of duties they were performing at the time.

The French executed their deserters.

The British executed their deserters.

The United States rarely executed a deserter but court martialed and sent them to federal prison.

Depends on which country you're talking about, but surprisingly few soldiers were executed for desertion in WW1.

Between 1914 and 1920, twenty thousand British and commonwealth personnel were found guilty of desertion. 3000 of them were sentenced to death, but nearly 90% had their sentence commuted. France executed 600, but Germany only executed 18. The US executed no soldiers in WW1 for desertion, and only 1 (Eddie Slovik) in WW2.

Russia and the Ottoman empires saw extremely high levels of desertion, due the collapse of their empires. Because the rate was so high it was hard to punish individuals.

Britain executed no soldiers for desertion in WW2 (the punishment was changed after WW1), despite there being over 100 thousand desertions. The Nazis executed over 15 thousand troops for desertion and the Japanese executed any soldier who even considered surrender (and soldiers who were going to be captured were expected to die as well) - but the highest number (uncountable) goes to the USSR - who executed any soldier who RETREATED under Stalin's 'not one step backwards' doctrine.

Shot by British officers.