In his younger years Ieyasu led his personal troops from the front. After Mikatagahara the bulk of the fighting were led by commanders loyal to Ieyasu.
As in many armies led by powerful daimyo, they consist of many clan or contingents led by veteran commanders, so the whole Tokugawa army would be a very colorful spectacle on the battlefield. When the Tokugawa troops go into battle, Ieyasu's very own troops often do not engage in combat, unless Ieyasu's HQ is threatened as in Mikatagahara. The Shimazu threatened Ieyasu's HQ at Sekigahara and the Sanada at the siege of Osaka.
Ieyasu's HQ would be a forest of white banners bearing the Tokugawa mon. Except at Sekigahara where he flew all white banners at his HQ. He had passed on his personal banners with the Tokugawa mon to his heir Hidetada.
Ieyasu would be protected by samurai bodyguards with Gold fan sashimono. He would be served by mounted tsukaiban wearing sashimono with the character 'Go', in at least two versions (black 'Go' on white, and white 'Go' on black).
In many of Ieyasu's battles and sieges, specific contingents with well-known commanders are mentioned. In this instances, Ieyasu's own personal troops with white sashimono did not go into action.
Check here for examples of some of the best known Tokugawa contingents:
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In the front rank of the Tokugawa are the Ii 'Red Devils' clad in red-lacquered armour and red banners. The rare example of a 'uniformed' contingent. Once they were formed they almost always led the Tokugawa attack. The first to engage the enemy, the first through a breach in a castle wall.
The other 'color' Tokugawa unit was the 'Yellow' regiment of Doi Toshikatsu which served under Ieyasu's heir Hidetada. Banners were all yellow, but not uniformed armour.
Before the formation of the 'Red Devils', the contingents of Honda Tadakatsu, Sakai Tadatsugu, Ishikawa Kazumasa, and Sakakibara Yasumasa are mentioned fighting as vanguard. The Ishikawa were the Tokugawa vanguard during the march to Nagashino, and Sakai Tadatsugu detached from the main Tokugawa army to attack the Takeda rear.
Examples of Honda and Sakakibara ashigaru armour bear respective mon, with examples of brown lacquered Sakakibara armour. Honda Tadakatsu's banners may have evolved through the years. His last banners depicted in the Sekigahara screens is the most famous, BUT his banners at the earlier battle of Anegawa appear different. Below is an example of how the Honda banners may have evolved.
Another bodyguard unit is that of The Okubo with their butterfly sashimono. At Mikatagahara they were part of the vanguard of Honda Tadakatsu and were the color guard for Ieyasu's Golden Fan standard during the fighting retreat.
Accompanying Ieyasu in all his battles until his death at the siege of Fushimi Castle was Torii Mototada. His unit would be placed at the head of Ieyasu's HQ.
Scroll down to see Sakakibara and Torii Mototada here:
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Also in the second link are the various Matsudaira contingents who served the Tokugawa.