1804- Yn ystod y flwyddyn cafwyd 656 o gychod ym Morthdinllaen.

1806- Cafodd deddf seneddol gadarnhad brenhinol ym Mai i godi glanfa ac adeiladau eraill ym Mhorthdinllaen.

1807- Dechreuwyd adeiladu y Whitehall ym Morthdinllaen, ynghyd a glanfa newydd. Gwnaed hyn gan obeithio y byddai Porthdinllaen yn cael ei ddewis fel y prif borthladd rhwng Prydain a'r Iwerddon, yn lle Caergybi.

1808- Ffurfiwyd 'Porthdinllaen Harbour Co.' gyda chyfalaf o £12,000.

1810- Gwrthodwyd y cais seneddol i sefydlu Porthdinllaen yn borthladd swyddogol rhwng Prydain a'r Iwerddon.

1804- During this year there were a total of 656 vessels recorded as being put into Porthdinllaen.

1806- In May, a parliamentary bill received Crown approval for new buildings and a pier at Porthdinllaen.

1807- The building of a new pier and Inn commenced at Porthdinllaen. This speculative investment was made when it seemed likely that Porthdinllaen would be chosen over Holyhead as the route to Ireland.

1808- Following on from the above, Porthdinllaen Harbour Co. was formed with capital of £12,000.

1810- The bill before parliament to constitute Porthdinllaen as a harbour for Irish trade was rejected.