This is a canon X OC story requested by @TheOther53. It's a Hamilton one shot, based in the revolutionary war era.

Dearest John,
New York is ever so lonely without you. I miss you every day, and am waiting every day to hear that the war is won and you're coming back to me.
I hope that, off in the war, you're doing well. I hope you're staying strong, as I know you are. I know it's hard sometimes, but I hope you remember how much we are all rooting for you here at home. It's been so long since I've seen your face, and cannot wait to see it again.
Stay brave, my solider.
-Belle.

My Beloved Belle,
How glad I was, this day, to receive a letter from you! The camp is very cold, and letters are scarce- I feel so lucky to be counted as one of the few who are in constant contact with their loved ones.
I hope that, at home, you're staying busy and reading often. I hope you're keeping faith- it is often all we have- and that these letters are not the only thing keeping you going, as they are for me.
My love, how I miss your beauty every day. Your wonderful auburn hair, and your shining eyes, and the way you smile before you turn my world upside down.
You are my own soldier, fighting every day at home. I hope you stay brave yourself, and await
Your John.

My Wonderful John,
Words cannot describe the gladness I feel at receiving a letter from you. It gives me hope that this war can still be won, encourages me to continue pushing for you.
I hope that your friend Alexander is writing to his own wife, Eliza. She seems worried whenever I see her, her face in a constant state of concern. With that child on the way, I believe she is afraid that he will pass away in the war before he sees his child.
Our correspondence makes me feel blessed, time and again- I have all of your letters saved in my hope chest. More than any fine linens or old silver, they matter to me.
Your dearest,
Belle.

My Beautiful Belle,
The war is nearly ended, we believe! You are the first person that I have shared the news with. General Washington gathered us all this morning and told us that he believes we can come to an arrangement very soon. As soon as he told us, I dashed off and wrote this missive as quickly as time allowed- please do excuse my dreadful penmanship.
As soon as we're home, I plan to see no one but you. In my mind, you wait for me by the door. I see you and hold you close, spinning you around in that way you never allow me to do. You kiss me and tell me how terribly glad you are to see me.
I wish to ask you a question, my Belle, and it is of the utmost importance. As you know, you mean the world to me. I wish for your heart, though a part of me says that I will never be enough for such a woman as yourself.
It is with great hope and affection that I ask you for your hand in marriage.
Hopefully awaiting your reply,
John.

Dear John,
I have read over your letter a thousand times, touching each letter of the line in which you ask the question which has kept me up all night.
My only answer, the only response I could ever give, is yes. I love you more than I can possibly express, and it would fulfill my greatest desire to be married to you.
To fall asleep beside you and awake to your smile, to see you come home to me at the end of every day, these have been my dreams since the first time your eyes met mine. I have finally realized what I've longed for, for so very, very long.
Come home to me quickly, love.
Your heart awaits you in,
Belle.