My great-grandfather, Alexander Houck Mosier, served in WWI with the 79th Division during the Meuse-Argonne Offensive, which took place from September 26, 1918, to November 11th, 1918. This is his story.
I have in my possession the transcription of a diary he wrote while deployed. A major help in writing this story is the book History of the Seventy-Ninth Division A.E.F. during the World War: 1917-1919, published in 1922. The book was extremely helpful, as Alexander had trouble spelling the French names. Reading along helped me to narrow down the towns he traveled through. I also have created a google map (https://www.google.com/maps/d/edit?mid=1Q49-SJTkOTM5jPSWg-qH7cAeFjOtm68&usp=drive_link ) , which plots where I think he was. Especially in later parts where his division is in combat, the pins mark the general area. The map covers his whole diary, so minor spoilers for where he traveled.
In this story, I have picked specific entries from his diary, marked in bold, to tell the story, with my comments/ summary along with quotes from the book, in italics. There are entries for each day, but some are removed to shorten the length of the story.
This story is continued from PART 3, Meuse-Argonne Offensive, Mountfaucon and Nantillois.

Thursday - 3 October - Clear. Nothing. Getting equipment and preparing to leave which we did about 7 PM. Walked all night, reached woods nearly about 6 AM. Men all very tired.

Friday - 4 October - Left about 2 PM, passed through Dugny Ancemont, reached Genicourt about 9 PM. Slept in billets.

Saturday - 5 October - Men have sore feet, checked up to find missing equipment. Stood first retreat. Cloudy and rainy in on our beds.

The 79th Division, after being relieved, were ordered to march without knowing where they were going. They hoped they would be off the front lines for a while, but an order came down that shattered those dreams: "Pursuant to Special Order No. 811, II Colonial Corps (French) dated 5th October, 1918, the 79th Division will relieve the 26th Division in the Troyon Sector during the night 7-8 October, 1918. The relief of the infantry and of the machine guns will be completed by the morning of 8th October."

Sunday - 6 October - Cloudy and cold. Men all laying around sick. Sent mail. Left town about 7 PM and hiked to woods and sleep on ground and wet. Very disagreeable.

The Troyon Sector was the setting for the major engagement before the Meuse-Argonne offensive, pinching out a German salient near the city of St. Mihiel. The intended goal was to push towards Metz, but plans were reduced to taking back the vital railroads the Germans had fortified. This campaign was mostly American fought and led. The American Expeditionary force proved themselves in this battle, which led to the Meuse-Argonne later on.

Monday - 7 October - Cloudy and foggy. Heard that central powers wants peace. Lay down about 6 PM then hiked to another woods and found little shelters and tents. Feel very bad.

Arriving in the sector, the infantry regiments were divided into two brigades, the 157th (313 and 314) and the 158th (315 and 316). The 157th Brigade was commanded by General W. J. Nicholson.

Tuesday - 8 October - Weather changeable. Hardly rations. Lay around in shelter. Packed up again and hiked to another front and relieved French about 2 PM. Very cold and sleepy. Must keep awake. Fresno (Fresnes-en-Woevre).

The front covered by the 79th division was on hills looking out over the Woevre, an agricultural region of Lorraine. The new front covered a distance of nearly nine kilometers and was of a peculiar nature. The main line of resistance ran from northwest to southeast along the summit of the Cotes de Meuse. The Cotes de Meuse were almost a continuous line of wooded cliffs, whose northeastern edges dropped precipitously to the plains of the Woevre. The line was wavy and irregular, following each projection thrust out into the plain by every cote (hill) which pushed boldly away from the main range. The observation from such an elevation was perfect. The Germans, to overcome the disadvantages of being watched from the heights, had withdrawn their lines about six kilometers, and the outposts of the Yankee Division (the soldiers that had taken the lines during the St. Mihiel campaign) had pushed after them, establishing their own outpost lines some 3 kilometers beyond the hills. As a result, the zone of observation covered the entire flat from the hills to the outpost line.

Wednesday - 9 October - Clear, heavy frost. One on guard at all times. Nothing to eat all day and night.

There were no plans from the Allies to attack, but it was not a time to rest. From the moment that the 157th Brigade took over the line of resistance it was apparent that the Germans were not going to let the sector remain a quiet one. On the first night in the Cotes de Meuse, the lines were treated to a vigorous bombardment consisting of both shell fire and gas.

Thursday - 10 October - Clear. Went back to dugout. Received a little soup and coffee. Rations had all been gassed. Meat turned green.

Friday - 11 October - Cloudy but warm. Everything quiet Thursday night. No food until late. Not very good. Quite a lot of shooting and noise at night.

The enemy evidently feared a renewal of the attack along this front, and used every effort to keep the Seventy-ninth Division well back from his lines by continual artillery fire. The original field order, taking over the sector, had mentioned that while the opposing line was held by a second or third rate German division which was uniformly unsuccessful in raiding, yet the German artillery was active, "especially on the towns in the Zone of Observation." This was soon found to be very true. Night after night the towns along the hills and in the plains — Fresnes-en-Woevre, Tresauvaux, Saulx-en-Woevre, Hannonville, Herbeuville, Combres, Wadonville-en-Woevre, and Mesnil-sous-les-Cotes — would be drenched with gas and raked with shrapnel and high explosive, which inflicted many casualties. Although the losses were light compared with the casualties of the battles before and after, still the "quiet sector," took its sizable toll.

Saturday - 12 October - Went back to dugout. More men gassed and very sick. Conditions very bad, no food and water. Was platoon runner to C Company. Was very sick/ Was to go to town and get sent to hospital but did not go. Back up at night and carried heavy packs. Were relieved by K Company about midnight.

The roads near the front, particularly those leading down into the plain, were watched carefully by the enemy and no living thing could move upon them without drawing shell fire. The supply wagons and trucks, especially, experienced difficulty in going to and from the front. Although this transportation only moved singly and at night, the Boche seemed to have an uncanny knack of shelling the roads at the summit of the hills in the line of resistance at such hours with both high explosives and gas. Every night, carrying details met the supply trucks and "took great burdens of rations and supplies by hand from the top of the cliffs down the steep and winding paths to the plains below and then for a long perilous trip out over the plains, along the shelled roads and through the soft marshy lowlands" to the men in the outposts.

A captain stationed in the reserve wrote this interesting description of the sights and sounds of the Troyon Sector:

"Perched up here, above the village of St. Maurice, in a rustic German villa that formerly served as head-quarters for a Brigade Commander, we are occupying the most picturesque sector we have yet struck. Stretching away to the East lies the broad, flat plain of the Woevre. Six kilometers away rises a misty line of hills which mark the main German line of defense. Thirty kilometers east of these hills Metz with its immense fortifications.

By day, the low-lying expanse of the Woevre lies in solemn stillness, no life or movement visible on its broad surface. At night, however, when Becker, Mitchell (the Y. M. C. A.) representative and I gather on the porch for observation and a discrete cigarette, there comes a miraculous change. Star-shells, red, green, yellow and white rise in rapid succession and throw their weird light over the plain below. Suddenly, far back of the Boche line, an orange flash stabs the darkness momentarily. Then comes an instant's silence, followed by a low whine which mounts into a crescento scream as an Austrian shell goes hurtling past our villa and bursts with a resounding crash at the cross-roads a half a mile or more behind us.

Meanwhile the German planes drone ceaselessly overhead and we get faint echos of an occasional sputtering machine gun fire which we surmise represents some kind of liaison signal."

Sunday - 13 October - Company returned to dugout used by K Company. Some very good eats, very tired, wet, cold and sick.

Monday - 14 October - Cloudy, had two formations to hear and article of war read. Cleaned guns very good. Still sick.

Apart from the shell fire and the gas, the third biggest threat was from influenza. A medical officer sent this in an order: "Influenza at the present time is pandemic. This disease is causing a very high mortality rate among our own troops and those of our allies. It is of importance, not only on account of its immediate effects, but also for the reason that it predisposes to, and is frequently followed by bronchitis, pneumonia and other respiratory complications. These complications have a very high mortality rate."

Tuesday - 15 October - Cloudy. Received clothes. Still very rainy.

Wednesday - 16 October - Rainy, very nice in dugouts with fire. Done nothing but lay around. Everything nice. See airplane battles.

Thursday - 17 October - Went on road detail to help 304" Engineers. Carried stone and detail to work on trenches at night up near German lines.

Friday - 18 October - Clear. Went on roads to clean mud. Very tired.

Saturday - 19 October - Cloudy. Cleaned up dugouts. See lots of big guns cracking.

Sunday - 20 October - Rainy. Went to hospital. Changed dugouts with Company CO B. Men had formation to check equipment. Still sick. Was marked quarters.

The week was “quiet” as far as the sector went, but on the 20th, spotters noticed multiple balloons going up and movement in the German lines.

Monday - 21 October - Clear. Went out on road detail. Still sick and could not do much work. Was called night to alert. Afraid of attack. Got grenade and ammunition.

On the morning of the 21st, a deserter made it through No Man’s Land and surrendered to the 313th, because he had heard that the Americans fed their prisoners well. He said more of his comrades were planning to surrender because conditions were so bad.

What the officers were interested in though, is that the deserter reported that a Bavarian regiment had come up to the front lines from the reserve. More observation balloons were spotted, prompting an order for the Allied reserve troops to come up to the front line.

Tuesday - 22 October - Cloudy. Was on K.P. Heard German patrols was captured. Lots of big shells fly over dugouts.

An Austrian regiment attacked a part of the 316th infantry in the early hours of the 23rd, but no Americans were killed. A prisoner was taken, who said: "At 3h his entire company of about 85 men left their reserve position about 3 km. in rear of their front lines and proceeded to their line of outposts. At a signal of three shots the company started over their line for Wadonville. Two platoons of 18 to 25 men each were sent ahead and the prisoner followed them as liaison agent. The prisoner further states that during their advance several of their raiding party were killed by their own barrage."

While in the Troyon sector, the 79th division received approximately 2200 replacements, men from the western and southern states, most who had never used a rifle before. The Division was here for two reasons, to train their new troops and guard the front line.

Also, there were some leadership changes. Colonel Sweezey had been evacuated after coming down with a high fever brought on by the strain of the Mountfaucon campaign. Eventually, after multiple transfers, Colonel William C. Rogers was appointed regimental commander.

While at Troyon, the 79th Division was transferred to the Second Army, commanded by Lieutenant General Robert L. Bullard in preparation for the next campaign, back to the Meuse-Argonne.