Final answer:
It is NOT true that Diomedes is a coward. As the youngest Achaean commander in the Iliad, Diomedes is notably bold and impetuous, and with Athena's inspiration, he wounds the gods Aphrodite and Ares.
Step-by-step explanation:
The character of Diomedes is a significant figure in Greek mythology, particularly in the context of the Trojan War as depicted in Homer's epic poem, the Iliad. Diomedes is known for being the youngest of the Achaean commanders, demonstrating traits of boldness and impetuosity in his actions. One of his notable feats includes wounding the gods Aphrodite and Ares, inspired by the goddess Athena. This act is a testament to his courage and prowess as a warrior. However, referring to the question, the option stating 'He is a coward' is NOT true about Diomedes. In fact, the tales from the Iliad and other sources demonstrate that Diomedes is anything but a coward, often portrayed as fearless and daring on the battlefield.