Final answer:
The Seabees significantly contributed to the Allied war effort during WWII by rapidly building ships and transport infrastructure, allowing for the efficient transportation of troops and supplies and enhancing the anti-submarine capabilities of the Allies.
Step-by-step explanation:
The invaluable asset that the Seabees constructed during WWII which helped sway the tide in favor of the Allies was the impressive feat of rapidly building ships and transport infrastructure, crucial for transporting troops and equipment to support the Allied forces both in Europe and across different theaters of war. In addition to technological advancements such as radar and sonar that proved devastating to German U-boats, the industrial might of the United States, exemplified by the construction of Liberty Ships, and the protection offered by naval destroyers played crucial roles in securing the Atlantic shipping lanes and ensuring a steady flow of supplies vital for the Allied war effort. The rapid shipbuilding capabilities were facilitated by exempting shipyard workers from military service, public relations campaigns to boost workforce numbers, the employment of a fabrication process with standardized parts, and the federal takeover of commercial ships to ensure a burgeoning and efficient fleet.