World War II memorial service at Tarawa for US Marines killed in battle there

The video discusses the aftermath of the battle of Tarawa, highlighting the significant loss of American lives. It reflects on the sacrifice made by 3700 American soldiers for a small island in the Pacific. The video concludes with a poetic tribute written by an anonymous marine, honoring the fallen heroes with a poignant epitaph.

What is implied by the phrase 'grave poetic epitaph' in the context of the text?

What imagery is used to describe the waves in relation to the fallen heroes?