Rule 4.4 Problem, Bombardment

[saracv3]

Here's the situation-
Two Soviet 8-10 mortars (same hex = 16 strength, direct LOS)! bombard a stack w a 3 strength German infantry, a leader, and 3 Soviet full-strength T26s, all stacked together in an assault battle.

Does the Bombardment follow rule 4.4.; in this case? 4 total units, friendly and enemy, are stacked together? Thus, the player would use one die roll for a result of the whole stack?