This is a fun one because, as many have noted, on the surface the plan is doomed to fail. If it's used to synchronize a bunch of humans in the form "attack on beat 3 of the last measure," it's just a very inefficient code, easily parsed and defeated.
To make this work, we have to stop thinking like computers. We have to stop thinking in terms of simple triggers and use the music for that it is intended for: to stir the human spirit.
You don't need music to synchronize a bunch of pre-planned activities. That is easily done using traditional communication means. The power of music is the ability to synchronize when the actions are much less planned. War is hell. Nothing ever goes according to plan. If you can adapt your behavior to fit reality, rather than slavishly following a plan, you have a huge advantage. Human beings are amazingly good at improvising, if given the opportunity.
The hard part of improvisation is keeping it cohesive. If you look at improve troupes, who make a living going out on stage and improvising, some of the most impressive content they produce is when one person improvises something outrageous and another person just runs with it, turning it into something funnier than the original content could have ever been, and something completely unpredictable.
To make this sort of humanity on the battlefield a reality, we need to focus not just on the composers. You need a conductor. A conductors job is not to stand up in front of a bunch of windbags and keep tempo. Any one of those windbags or fiddlesticks could keep tempo on their own. The job of a conductor is to inspire and direct the human spirit deep within those skilled musicians to form a unified spirit so potent that many poets have theorized it may be capable of stopping war all together.
In that spirit, the notes on the page are really just a framework. The real music comes from the spirits of the musicians unifying and becoming more than they were before. A skilled conductor brings out the very best in each and every one of us on stage (and ideally, in every one of us in the audience).
If I may quote an answer that I gave to a question on Music.SE years ago:
[...] At the epitome of skill, the conductor becomes a peer and a trusted friend. At some point, you can't go any further without losing yourself in the music. Someone is going to have to find you again. That person is the conductor. I will never forget a beautiful violin concerto done by a brilliantly talented violinist. She started the concerto with her opinion of what the music should sound like in one of the classic opening concerto solos. The conductor smiled patiently, and let her take control of the music completely (he even adjusted the tempo to suit her). As she continued the ferocious stream of notes, you could see her start to destabilize -- the music literally was taking control of her. The tempo wavered just a little, suggesting ruin.
Then, in one moment, the conductor changed how he was conducting ever so slightly and locked her playing into something he had some control over. He then tied her emotions directly into the orchestra, so she was no longer just a soloist, but part of the orchestra.
Once she was assimilated, he pushed her harder. He drove her further into the emotion and speed until I don't think she could have stopped if she had tried -- her fingers would have unraveled before she could have stopped the violin from playing its notes.
Half way through the final movement, he calmed things down and let her lose. She finished off the concerto in her style, under her own power. The applause at the end was deafening. She proudly took a bow for her skilled work, but you could see from how she shook while bowing that the conductor had taken her to a level of skill she wasn't even aware she had, let her grasp the stars, and then come back safely.
That, my friend, is what you have a conductor for.
Good luck, Mr. Great Computer.