user
Instruction
Answer the question based on the provided table.


Table
Table Title: 'Summary of raiding history' regarding 'German submarine U-775'
Table Content:
| Date | Name | Nationality | Tonnage | Fate |
| --- | --- | --- | --- | --- |
| 6 December 1944 | HMS Bullen | Royal Navy | 1,300 | Sunk |
| 28 February 1945 | Soreldoc | United States | 1,926 | Sunk |
| 6 March 1945 | Empire Geraint | United Kingdom | 6,991 | Damaged |


Question
How effective were the U-775 submarines during the war? 


Answer Format
The final answer should be a sentence and use the following format:
```json
{
    "answer": "your_generated_sentence_here"
}
```
rule
["German submarine U-775 sank one merchant ship, for a total of 1,926 gross register tons (GRT), one warship sunk (1,300 tons) and one merchant ship damaged (6,991 GRT)."]