Choose a target audience. Some historical morale songs were written specifically for the troops, whereas others were written to encourage patriotic supporters on the home front.
Write lyrics that are encouraging and uplifting. Use imagery that paints pictures of positive concepts like victory and family. Create lyrics that allude to progress and a better future.
Write the melody of your song in a major key. Major keys naturally sound happy, whereas minor keys tend to have a sad sound.
Write your song in 3/4 time. This means that each measure of the song gets three beats. This rhythm is commonly known as a "waltz" rhythm. While you can write morale songs in other rhythms like 2/4 and 4/4, the 3/4 rhythm has a lighter, more whimsical feel.
Use syncopation in your song. Syncopation is the accent of a beat that is usually weak. This creates unexpected energy within a song.
Include whimsical additions to your music such as a whistling section or a call-and-response in which one person or group sings a word or phrase and another person or group answers this musical word or phrase.