Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
German submarine U-338
Table title:
Summary of raiding history
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Date </th><th colspan=1 rowspan=1 > Name </th><th colspan=1 rowspan=1 > Nationality </th><th colspan=1 rowspan=1 > Tonnage (GRT) </th><th colspan=1 rowspan=1 > Fate </th></tr>
<tr> <td colspan=1 rowspan=1 > 17 March 1943 </td><td colspan=1 rowspan=1 > Alderamin </td><td colspan=1 rowspan=1 > Netherlands </td><td colspan=1 rowspan=1 > 7,886 </td><td colspan=1 rowspan=1 > Sunk </td></tr>
<tr> <td colspan=1 rowspan=1 > 17 March 1943 </td><td colspan=1 rowspan=1 > Fort Cedar Lake </td><td colspan=1 rowspan=1 > United Kingdom </td><td colspan=1 rowspan=1 > 7,134 </td><td colspan=1 rowspan=1 > Damaged </td></tr>
<tr> <td colspan=1 rowspan=1 > 17 March 1943 </td><td colspan=1 rowspan=1 > Granville </td><td colspan=1 rowspan=1 > Panama </td><td colspan=1 rowspan=1 > 4,071 </td><td colspan=1 rowspan=1 > Sunk </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 17 March 1943 </td><td class="highlighted"  colspan=1 rowspan=1 > King Gruffydd </td><td class="highlighted"  colspan=1 rowspan=1 > United Kingdom </td><td class="highlighted"  colspan=1 rowspan=1 > 5,072 </td><td colspan=1 rowspan=1 > Sunk </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 17 March 1943 </td><td class="highlighted"  colspan=1 rowspan=1 > Kingsbury </td><td class="highlighted"  colspan=1 rowspan=1 > United Kingdom </td><td class="highlighted"  colspan=1 rowspan=1 > 4,898 </td><td colspan=1 rowspan=1 > Sunk </td></tr>
</table>
Question:
What British ships did the U-338 sink on March 17 and what were their tonnages?
Answer:
On March 17, U-338 sank two British merchant ships: the 4,898 ton Kingsbury, and the 5,072 ton King Gruffydd.