Rutherford Hayes was a general in the Civil War and always preferred "General Hayes" as a mode of address, considering his wartime years and contribution more important than his presidency. The Hayes Center has his original telephone book, which lists him as "General Hayes" as opposed to "President Hayes." Hayes was elected to Congress while still in the army, but refused to campaign, saying that, "an officer fit for duty who at this crisis would abandon his post to electioneer... ought to be scalped."
Lucy Hayes was also active with his regiment:
Lucy Hayes routinely visited his camp and assisted in military hospitals. She also secured supplies from Northern civilians to better equip the Union soldiers. Soldiers in the Twenty-third Ohio nicknamed Lucy Hayes "Mother of the Regiment" for her contributions to their welfare.
To go with this post, I'm including a few of their Civil War letters as well for you to enjoy:
Camp Reynolds- Jan 25th 
Dear Uncle- [this would Sardis Brichard]
You will be surprised to know we are in Camp- Birch and Webb are perfectly happy. We had a pleasant trip - though the ride from Camp Piott in Ambulance for 28 miles was sufficiently muddy and as rough as heart could wish- we reached Camp last night and were so glad to find all well - by some means I have lost a day in the week and cannot yet believe that it is Sunday- and as it is very muddy I have not been out through the Camp but from our Cabin we have a beautiful view and the roaring of the waters all make it very delightful- I do not think Uncle that I answered your very kind letter with Christmas enclosed for the boys- it was not neglect- but Mother was then quite sick- then myself for a few days and lastly little Rud quite ill then the start for Va- occupied my time so closely- the little fellows were kindly remembered by their friends- Birchie bought a very interesting book with his portion - while Webb Joe and Rud being supplied with all toys added their portion to their fund- so all thanked Uncle for Christmas
The little girls were quite well when I left they come to see us quite often, but not as much as I would like- they are cheerful and happy.
I wish Ruddy Platt was with us- what a merry time they would have.
My Regards to all
Cincinnati- March 24th 63
We reached home safely Sunday evening between five and six- the boys were very good- giving me no trouble- and then Mr Little took B to see the machinery- while Mr Forbes was constant in his attentions to them- every thing was pleasant- the Clerk Mr Sontag- was polite and attentive to me and the boys- I always meet with Kindness- and will always try more than ever- to return what I always receive- Dr and Mrs McCune are agreable [sic] acquaintances- and the trip from Charleston to Cincinnati was pleasant- until we came in sight of the City- then I realized the change- I had left you- after so much happiness dearest- the pain of parting is more severe- by the time we reached home we were ready to cry- Birch and I- and after meeting with such a cordial loving greeting- they were not looking for us, and yet were expecting us- Birch took a good cry- and I could hardly avoid following him (through sympathy). Rud was wild with joy- Joe dear little fellow- with a pleased joyous look- doubting somewhat- but in a few moments laughing and clinging to me- home is sweet- but oh we do miss you so much- Mother looks as well as usual and is in very good spirits- all are happy- but we would willingly give you the benefit of our society for a little while-
School opened this morning- Rud is really very smart but poor Webb- it is a hard task for him- but still I have hopes- Mr George Carlile died on Sunday after a short illness- Typhoid fever- Sunday evening little Eva Mitchell- (living in Bates house)- she was Birchies age a very pretty child- if you remember the little girls skating she was the most graceful and rapid- her death was very sudden- sick only that day- I have not seen any of our friends yet- hear all are well- I shall send this by Mr Forbes thinking you will get it sooner- than Mail- Little Joe is walking around-
All join in love- Every thing is very high- do not know whether we will be able to get any butter for Joe or not- Write soon-
Yours Affec. L.W.H.