Operation Hopper - Air Raid in the Anchorage
After taking part in the successful landings on Sicily during Operation Husky and being moved into reserve both 40 and 41 Commandos were chosen for an operation in coordination with a push north of Catania by 8th Army.
Codenamed Operation Hopper, the plan was to put two Commandos astride the road and rail lines of communication north of Catania to prevent or delay German reinforcements from interfering with 8th Army operations.
The Commandos embarked the Dutch landing ships Queen Emma and Princess Beatrix in Syracuse and the ships anchored in the outer harbour in preparation for departure. The operation was cancelled that same evening because there were reports of German forces moving into the area chosen for the landing.
Later that night during an air raid, both ships were bombed and tragically 40 Commando suffered 71 casualties of which 13 were killed, 41 Commando lost one killed and nine wounded. The Commandos were landed the next day and went into bivouac where they remained throughout July.
The Commandos were not used again in Sicily as the developing operations better suited line infantry.
They continued to train for their next operations - 40 RM Cdo in Operation Ferdy at Vibo Valentia on the toe of Italy and 41 RM Cdo in Operation Avalanche at Salerno. 
HMS Queen Emma was originally Koningin Emma one of two Dutch ships to escape to England at the start of World War Two.
Her sistership was HMS Prinses Beatrix. Although often named as HMS Princess Beatrix she was commissioned as HMS Prinses.
On 17th July 1943 HMS Queen Emma was in Augusta Harbour Sicily with 40 Royal Marine Commando on board when there was a bombing raid on the harbour. This caused numerous casualties and damage on board when concussion and shrapnel from a bomb caused a box of grenades to go off on the mess deck.
Extract from the 40 RM Commando war diary
(Source: National Archive file ref ADM 202 / 87)
15 July 1943
1300hrs -arrive SYRACUSE harbour1500hrs disembark Syracuse
16 July 1943
1200hrs - Cdo embark - Force11 M.V Queen Emma1400hrs - sail from Syracuse harbour1600hrs - arrive Augusta harbour1800hrs - Cdo informed operation cancelled
17 July 1943
0200hrs - Air attacks on harbour start0210hrs - M.V Queen Emma suffered near miss; concussion and shrapnel from bomb caused a box of grenades to go off on the mess deck occupied by B and P troops, many casualties occurring. Capt. Stiebel and Surg Lt Cmdr Pryde killed , 13 OR's killed and 58 wounded. 
Related Royal Marines ‘Dits’
References/ further Reading
 The 80th anniversary of Husky - 40 and 41 Commandos in Sicily - Lt Col George Gelder (Retd) - Globe and Laurel July-August 2023)
 Commando Veterans Archive - 40RM Commando - HMS Queen Emma