After pretty much a stalemated war for the most part
(Even the arrival of battle hardened troops from the russian front couldnt break it)
The kaiser of germany decided to use a ruinous naval policy
Germany U-boats would destroy all ships going to britain france belgium and italy
This turned out to be a really bad idea as several countriws declared war on germany after this
Most notably the united states and japan
(Something that also worth mentioning is that germany tried to get mexico to attack the united states)
Japan captured all german colonies the pacific including palau and samoa
Germany was already blockaded but there were blockade runners who brought in supplies from said islands
Germany barely had enough supplies to finish their final assault