3 ms·> Bitcoin had been 51% attacked before Are you thinking of Bitcoin Gold?by paulgb 4y ago> Bitcoin had been 51% attacked before Are you thinking of Bitcoin Gold?adastra22 4y agoNo, Bitcoin. Google GHash.ioKbelicius 4y agoGHash.io controlled 51% of hash power for a short time, no attack was carried out. So no, there wasn't a 51% attack on BTC.