A weeklong series of commemorations begins on November 4 in France to mark the 100th anniversary of the end of World War I, with some 80 world leaders expected to attend.

French President Emmanuel Macron hosts ceremonies on the battlefields across the country where hundreds of thousands of men died in muddy trenches during long stalemates between the Allies and German forces.

Among the WWI sites he will visit are Verdun and the Somme, where British Prime Minister Theresa May is also expected to participate in ceremonies.

U.S. President Donald Trump and Russia’s Vladimir Putin are among those expected to attend ceremonies in France. U.S. officials have said it is likely the two leaders will briefly meet at some time during the commemorations.

The remembrances will conclude at Paris’ Arc de Triomphe on November 11 -- a century to the day since the day the fighting ended at 11th hour of the 11th day of the 11th month.

Trump, Putin, and German Chancellor Angela Merkel are expected to participate in the final ceremony.

French officials have promised tight security after a series of deadly attacks in France blamed on Islamic militants over the past three years.

Most World War I battles were fought in France and Belgium.

The war resulted in the end of the Ottoman, Russian, German, and Austro-Hungarian empires, and at least 16 million people are estimated to have died due to the conflict.

Based on reporting by AFP, The Guardian, and Sky News