So I was talking to my father who Is a former marine and he said it was more to do with politics than any thing else that there were no marines at d day and it was becuase the army didn't want then stealing all the spotlight and credit for it like they did in ww1 sometimes. Is there any truth to that?
No. The Marines only had six divisions during the Second World War and all of them were deployed in the Pacific where their amphibious landing specialty was being utilised far more regularly during the island hopping campaign. The army divisions that took part in the D-Day landings were only required to undertake a single landing, once they were ashore, the rest of their war would be conducted on land. They could be trained to undertake that one landing quite easily.
It would have taken too long to transfer the marines from the PTO to the ETO to undertake that one landing and then transfer them back to the Pacific. That also doesn;t take into account that at the time of the D-Day Landings, some of the Marine divisions were undergoing rebuilding after the New Guinea campaign or were about to launch their own landings on Saipan and Guam. One of the divisions, the sixth, hadn't even been deployed yet as it was still being formed.
In addition to what has been said, I will point out that Marines were used on D-Day. That is, Royal Marines were.
47 Commando Royal Marines formed the right flank of the British landing force at Gold Beach, and after securing the beachhead, swung west to Port-en-Bessin to link up with the Americans at Omaha. This was achieved on 8 June. At Juno Beach, the Canadians were supported by 48 Commando RM on their left flank, who like at Gold had the responsibility of pushing east to seize the town of Langrune-sur-Mer and link up with British forces on Sword Beach.
At Sword, Royal Marines were extensively represented in the assault brigades: as part of the 4th Special Service Brigade, 48 Commando RM landed at Oboe Sector, again to secure the flank of the beachhead at Luc-sur-Mer, while 41 Commando landed next to it in Peter Sector. 45 Commando landed on the very eastern flank of the beachhead as part of Lord Lovat's 1st Special Service Brigade (which you may have heard of before; Lord Lovat was the chief of the Scottish Highland Clan Fraser and had his personal piper, Bill Millin, pipe his men to shore) to secure the flank of the invasion on the River Orne.
Sources:
James Holland, Normandy '44: D-Day and the Battle for France
Steven J. Zaloga, Atlas of the European Campaign, 1944-45