The 7,5 cm leichtes Infanteriegeschütz 18 (7,5 cm le.IG 18) was designed between 1927 and 1932 by Rheinmetall, to provide German infantry with a mobile and effective fire support weapon. Protected by an armored shield, the gun was an effective design, with 12,000 manufactured between 1932 and the end of the war.
Each Grenadier Regiment had a infantry howitzer company similar to the American Cannon Company. Like the American Cannon company infantry howitzer company was manned by infantrymen. This company has three two gun IG 18 platoons along with another platoon of two S.IG 33 infantry howitzers. These infantry howitzer provide close artillery support to the infantry battalions.
The IG 18 is an effective tool to suppress enemy attacking infantry, anti-tank guns, or MGs in an opposing hedgerow.
Their higher fire rate makes them more effective against multiple targets than its bigger brother the IG 33. Their long 1000m range allows them to hold open fields at a distance. They are effective when paired with AT guns, as they will usually deal with any advancing infantry at range. Their effectiveness decreases at close range, as the angle of the cannon means that they cannot hit targets at close range.
Whereas all Sherman tanks can and should attack the german PaK 38 50mm (at 1000m range the AT gun has a very low chance of penetrating frontal, and at 800m and 600m the Sherman do additional damage with their 12,7mm and then with the 7,62mm MGs!) especially when within a Leader aura to receive only half the supression damage, none of the German medium tanks (Panzer III, Panzer IV and StuG III) should attempt to attack a M1 Gun 57mm!
One or multiple Sd.Kfz. 250/8 might be able to supress the AT gun before it can do too much damage. But - when available - IG 18 or S.IG 33 should be used against allied AT guns.