שמואל ב, פרק י״ח, פסוק א׳

As the military campaign approaches, David takes careful steps to prepare and organize his forces for the upcoming battle. His preparation unfolds in two distinct stages [מלבי״ם]. First, he conducts a military census to determine the exact number of soldiers who have gathered to support him [מצודת ציון, ביאור שטיינזלץ]. Once the troops are counted, David moves to the second stage: appointing leaders to guide them. He assigns commanders over groups of thousands and hundreds.

The primary approach among commentators is that this structured division is designed to establish excellent military order and a clear chain of command. Such careful organization of forces is seen as a critical factor in securing victory on the battlefield [רלב״ג, אברבנאל]. Additionally, organizing the troops under specific commanders directly follows the Torah's instructions for going to war. It represents the final step of military preparation, taking place just after any fearful or fainthearted soldiers have been removed from the army's ranks [רלב״ג].