You might be interested in these threads on battle speeches and how commanders made themselves heard to their armies:

Where there really dramatic speeches given before battles like we see in film? and Did great military generals and leaders give speeches before battles like you see in the movies? And if so, were only a few able to hear it? by /u/XenophonTheAthenian

In movies like Braveheart, leaders often give inspiring speeches. Assuming this was accurate, how would thousands of foot soldiers hear this leader right before battle? by /u/Iphikrates