"246 BT-7s and ten T-26s" - change to "10 T-26s" for the sake of consistency.
"This advance allowed Kolessa to successfully break out to the Kämärä station area late that day." - Do you mean later that day, too late to be useful or towards the end of that day?
"The 13th suffered casualties of were 234 killed, 484 wounded, and 23 missing." - Reword.
Include the invasion of Estonia in the infobox.
Shouldn't the category be Military units and formations established in 1932?