August 5th-10th - In the space of five days slow Halifax/UK convoy SC94 (33 ships) is attacked by a total of 17 U-boats and loses 11 merchantmen. On August 6 - Assiniboine surprises U-210 on the surface in fog. In a strange but deadly close range gun action Assiniboine finally rams the u-boat, at a cost of 1 killed, 12 wounded, and extensive damage to the bridge and gunshields by the U-Boat's guns.

August 8th, British corvette Dianthus also with C1 group, depth charges and rams U-379. Four more U-Boats are damaged in defence of the convoy.

This is part of the official report filed by J. H. Stubbs, Lieutenant Commander R.C.N, captain of the Assiniboine, for the afternoon and evening of Aug 6, 1942:
https://www.junobeach.org/canada-in-wwii/articles/submarines-attack-in-the-st-lawrence/hmcs-assiniboine-and-the-destruction-of-u-210/

I closed on the U-boat to ram at full speed, having housed the ASDIC dome, with a 50 foot pattern ready. He opened fire with all his guns and for about 35 minutes the action continued at a point blank range of about 100 to 300 yards. A second degree fire broke out on the starboard side at the break of the forecastle and spread almost to the bridge and through the sick bay flat. The enemy took constant evading action and I was forced to go full astern on the inside engine to prevent him getting inside our turning circle, which he was obviously trying to do. It was impossible to depress the 4.7" guns sufficiently at this range, but I ordered them to continue firing, more to keep the guns' crews busy while under fire than from any hope of hitting. One hit was gained on the conning tower however During most of the action we were so close that I could make out the Commanding Officer on the conning tower bending down occasionally to pass wheel orders. A gun's crew appeared, on the deck and attempted to reach the forward gun but our multiple .5's successfully prevented this.

Three or four times we just missed him. The officers left the conning tower in order to dive, and in the few seconds during which he was on a steady course we rammed him just abaft the conning tower. He was actually in process of diving at the time. I turned as quickly as possible to find him surfacing again but slightly down by the stern, still firing and making about 10 knots. After a little manoeuvring, we rammed him again well abaft the conning tower and fired a shallow pattern of depth charges as we passed. Also one 4.7" shell from "Y" Gun scored a direct hit on his bows. He sank by the head in about two minutes. "Dianthus" appeared out of the fog just in time to see him go. The yell that went up from both ships must have frightened U-boats for about 10 miles in the vicinity.

Ten prisoners were picked up by "Assiniboine", 28 by "Dianthus" six of which were later transferred to "Assiniboine". While they were being separated the prisoners "Heiled" several times at the top of their voices. When received onboard, officers, of which there were two, and ratings, were segregated. Casualties sustained amounted to one rating killed, one officer and twelve ratings wounded. Ship's plating was punctured in dozens of places on the water line, gun shields, bridge, range finder, funnels and searchlight platform. Several bullets penetrated to the wheel house, which probably accounts for the lack of track charts for this particular period. All compartments below the waterline, aft to the provision room were flooded, and extra shores were placed. A/S and R.D.F. were out of action as well as gun circuits and certain lighting circuits. It is notable that two of the most delicate instruments in the ship, the plot and the gyro, remained intact.

In view of all this I decided the ship must return to St. John's forthwith. I believe the submarine did not dive because he hoped to get away from us in the fog, as during the whole action visibility was 500 yards or less. Also the fact that clouds of smoke and flares were issuing from our starboard side may have led him to believe that we were seriously damaged. It was also conceivable that if we had depth charged this U-boat during the forenoon, he may have been effecting repairs and did not like to dive except in case of emergency. The plot shows that from sighting at 1125 until sinking, the U-boat maintained practically a steady course of 025 degrees.