If you don't mind, could you elaborate further on the Laird Rams? It's a potential POD I almost never see fleshed out, if at all.
I'm going off memory here, so bear with me. In 1863 the Union was suffering from the effects of Confederate commerce raiders causing much alarm and damage, two in particular the
CSS Florida and the
Alabama were causing much mischief. The greatest problem was that both had been built in British yards and had been allowed to make a clean break. The British, who did not particularly care about this in 1861-62 were being put under increasing pressure by the American government to watch the ships being built in their harbors, but there was some resistance to this at first. With the Laird Rams, two very obviously armored military ships, there was a lot of subterfuge to make them look like they were being outfitted for Egypt. In reality, hulls 294 and 295 were going to be the
North Carolina and
Mississippi once they were fitted out. In September of 1863, it was beginning to look like they might slip past the customs officials in Liverpool and sail for North America. OTL Lincoln and Seward exerted as much pressure as they could for the British to find out just who the ships were being built for, and act as neutrals by stopping the ships if they were being outfitted for the CSA. Charles Francis Adams, ambassador to the UK, famously said "
It would be superfluous in me to point out to your lordship that this is war." when discussing the issue with the British foreign minister, who did not want to interfere. Historically, the British detained the ships, but had they not there is every indication that the US would have been willing to do
anything to stop them. This might include something like the
Bahia Incident where a Union warship violated the integrity of Brazilian waters. The British, sensitive about that kind of thing, would have no choice but to retaliate and take the ships back, the Americans couldn't really let that happen and so...
Wild speculation, but you would have a bad diplomatic incident sometime in September-October 1863, the British would remember the
Trent and probably decide that had to issue a sharp lesson while the Union would remember the raiders and be very unsympathetic to British protests or reprisal.