How does a commander estimate enemy's losses?

Upvote:2

The issue you raised here has different perspectives:

Battle Damage Assessment: this is basic: I strike you, then I go to see what damages I've done
Recon: I recon your forces at any time in order to know what is your power in front of me
Intelligence: I assess your power overall (for example Eastern front assessed by British intelligence)

For the first part, two means are available:

Check the battleground for losses: count bodies,destroyed vehicles... This solution, available on land and rarely on sea (harbours) gives an minimal estimate of ennemy losses. This is also very useful because it gives certain, total losses (nothing could be repaired if it is left on the battleground I control). In the air and on the sea, BDA is more difficult because you need to find out if the ennemy you tracked (with eyes, radar..) is no more here because you killed him or because he fleed.
Recon should be performed for many reasons, mainly for assessing enemy strength and where it is positionned. The variation of ennemy's strength gives you estimate and should be taken with caution: an ennemy vehicle you don't see anymore could be lost.. or camouflaged and ready to attack from an unexpected direction. In WW2, recon was performed by air and light infantry or light vehicles means.
Intelligence is broader: it gives you losses on the long run, and how they are replaced or not by ennemy industry. So it is very useful even if you already have the two others methods, but an intelligence report won't tell you "Pilot X killed ennemy aircraft Y" In WW2, intelligence was HUMINT and SIGINT.

So, in WW2, that's how a commander estimated ennemy losses. Now, why was it so bad in specific situations such as Stalin in 1941? Because:

BDA was overetimated because all the chain from soldiers to generals tried to present them as the best
Recon was mainly not performed: too early for partisan to give information, no air power for recon, lack of light vehicles. Only available mean, cavalry, focused on raiding rather than on intelligence gathering
Soviet intelligence on Germany was good for political, industrial part. Not for the military frontline assessment. (Germany's intelligence was even worse on every aspects)

totalMongot 6454

Source: stackoverflow.com