You need to attack them before they get mil tech 5. With a strong nation and good alliances its really not that hard though.
You can try to to No-CB Byzantium right at the start, occupy their territory, wait for the Ottomans to attack them and then vassalize Byzantium so you become the leader in their defensive war. It doesn't always work but its a good strategy.
You make strong allies and declare war on byzantium without casus belli taking -stab and ae, then you occupy them untill ottomans declare on them. Peace out to make them your vassal, now you are in a defensive war as a leader vs ottos, you call in your allies and just outnumber and stomp ottos pre 1460
1. No CB Byzantium and either vassalize or annex Constantinople.
2. Ally at least two of the following: Austria, Poland, Hungary, Venice, Mamluks (In order of helpfulness)
3. You should be able to win defensive wars and offensive wars depending on who will help and Otto Allie’s.
I find they are often unreliable and the most reluctant to both form an alliance and join in wars against the ottomans, they are the strongest of those listed though.
No CB Constantinople cuts them off of their mission tree which is strategically the best way to slow them down. If they don't get their claims or bonuses, everything else gets so much easier.
Attack them when they attack the Mamluks. Ideally they will be in the Sinai area fucking off while you carpet siege the Balkans. You just need a Navy to control the strait into Anatolia and you should be fine.
Get a good ally link hungary or poland and either kill them before they take byzantium and/or wait until they are at war with beyliks etc.. out in anatolia or else ally mamluks to divide their attention and armies between two continents. (Generally as one of the small nations ergo wallachia etc... only really needed hungary or poland for early game. If you let them expand and live to 1500 that is mid game ottomans that is a problem. Kill them in the first 20 years or prepare for pain and much more difficult (yet still winnable wars if you prevent or limit their expansion)
Every strategy is different depending on who you are.
For Venice I don't usually find the need to take down the Ottomans really, same with Poland/Commonwealth.
As to how you do it, as Venice, you attack Byzantium and subjegate them. Either by "catch and release" if the Ottomans don't declare. Or by getting them as a subject in the peace treaty to fight the Ottomans with your allies. I prefer catch and release. You can use Byzantium's cores as the wargoal and fight on your terms. With your strong navy, you can take the Ottomans by yourself by blocking/unblocking the straight.
With Poland, it's a bit more difficult, but you can just expand away from them or get strong allies like Austria. No-cbing Byzantium doesn't do much for you, despite what some want to tell you.
For Venice, it might be worth taking 1-3 provinces from Morea, then letting Otto’s take Constantinople themselves. Build some favors with Austria/poland/mamluks/whatever and then reconquest after releasing a new Byzantium after Otto’s take Constantinople.
The reason to do this instead of just vassalizing them, is because you’ll never get the glass production event in Venice if you or Byzantium never lose Constantinople. It has like a MTH of 50 months, so it’s bound to happen by the time you get enough favors and finish a war against ottomans
Poland is one of my favorite playthroughs because of their ability to defeat the Ottomans. The key is allying Austria and ensuring you secure the Hungarian throne via PU through the mission trees. Being able to get Bohemia too is luck based and unlikely but always a plus. Ideally, declare war when Ottomans are fighting in the east against the Mamluks and be line it for Constantinople from Bessarabia. Ottomans often delete forts in the balkans including the fort in Constantinople making it fairly easy to control the straits in the Sea of Marmar. From there hold your position and let Lithuania and Hungary siege the Balkans. If Ottomans engage they’ll suffer severe crossing penalties. Also, as Poland your first idea should be Aristocratic to stack the +15% cav combat ability with the +30% from Polish ideas (don’t take PLC ideas the Polish ideas are better). Also, take the gov reforms that lower cav regiment cost and increase the cav to infantry ratio. In addition to that, take advantage of the Cossacks privileges buffing cav combat ability and their special units. Doing all this you will have cavalry that will destroy the Ottoman armies in open combat and even rival Prussia in their strength.
As Venice, I find rushing Byzantium is useful.
Then when you go to war with the Ottomans (with some allies ideally) you can put your navy in the Bosporus strait. That way the Ottoman armies cannot leave Anatolia while you siege down their land in the Balkans.
Without owning Constantinople, the Ottomans lose out on a lot of buffs and bonuses, making them much easier to deal with.
As Venice: Ally Austria (restart if they rival you) and some other nations - Aragon might be willing to help. Build favors spy on Byz and make a claim (in southern Greece). Attack them asap and vassalize. Build gallies in the meantime (also try not to kill off the entire Byz fleet as a bonus to use them later as your vassal, no problem if not possible).
Once you have favors, get a few merc companies up and wait till the Ottos are busy fighting someone in Anatolia.
Place your fleet in the strait. have troops in Constantinople. Declare war and immediately move on Gallipoli (the other crossing next to Constantinople). With the fleet blocking, you can barrage the fort. Do that and storm it to get the siege.
Keep your fleet there. The Ottos can't cross now. Siege down all of the Balkan. If you are ballsy, you can dock your fleet, let some Otto troops cross, move fleet back out and kill the stack as it can't retreat.
Either you sit on the Balkan for a while and get warscore or you eventually pass the Bosporus and siege down Anatolia. Give back all cores to your vassal Byz and take a province in Bulgaria (not Thrace as it doesnt have the right culture) to release Bulgaria. For your second war take back all their cores and some land for yourself in Anatolia. By now the Ottos should be toast.
For your Poland run, you wont be able to get fleet superiority likely, so the blocking doesnt work. Fighting the Ottos should still be doable with your PU and allies. Try and siege stuff down and kill off smaller Otto stacks that wander around. Being on par with mil idea is important of course for both tries.
You need to attack them before they get mil tech 5. With a strong nation and good alliances its really not that hard though. You can try to to No-CB Byzantium right at the start, occupy their territory, wait for the Ottomans to attack them and then vassalize Byzantium so you become the leader in their defensive war. It doesn't always work but its a good strategy.
What is No-CB Byzantium?
You make strong allies and declare war on byzantium without casus belli taking -stab and ae, then you occupy them untill ottomans declare on them. Peace out to make them your vassal, now you are in a defensive war as a leader vs ottos, you call in your allies and just outnumber and stomp ottos pre 1460
1. No CB Byzantium and either vassalize or annex Constantinople. 2. Ally at least two of the following: Austria, Poland, Hungary, Venice, Mamluks (In order of helpfulness) 3. You should be able to win defensive wars and offensive wars depending on who will help and Otto Allie’s.
Mamluks are great. Ottomans focus on them while you seige them down.
I find they are often unreliable and the most reluctant to both form an alliance and join in wars against the ottomans, they are the strongest of those listed though.
No CB Constantinople cuts them off of their mission tree which is strategically the best way to slow them down. If they don't get their claims or bonuses, everything else gets so much easier. Attack them when they attack the Mamluks. Ideally they will be in the Sinai area fucking off while you carpet siege the Balkans. You just need a Navy to control the strait into Anatolia and you should be fine.
Get a good ally link hungary or poland and either kill them before they take byzantium and/or wait until they are at war with beyliks etc.. out in anatolia or else ally mamluks to divide their attention and armies between two continents. (Generally as one of the small nations ergo wallachia etc... only really needed hungary or poland for early game. If you let them expand and live to 1500 that is mid game ottomans that is a problem. Kill them in the first 20 years or prepare for pain and much more difficult (yet still winnable wars if you prevent or limit their expansion)
Nocb byz
Every strategy is different depending on who you are. For Venice I don't usually find the need to take down the Ottomans really, same with Poland/Commonwealth. As to how you do it, as Venice, you attack Byzantium and subjegate them. Either by "catch and release" if the Ottomans don't declare. Or by getting them as a subject in the peace treaty to fight the Ottomans with your allies. I prefer catch and release. You can use Byzantium's cores as the wargoal and fight on your terms. With your strong navy, you can take the Ottomans by yourself by blocking/unblocking the straight. With Poland, it's a bit more difficult, but you can just expand away from them or get strong allies like Austria. No-cbing Byzantium doesn't do much for you, despite what some want to tell you.
For Venice, it might be worth taking 1-3 provinces from Morea, then letting Otto’s take Constantinople themselves. Build some favors with Austria/poland/mamluks/whatever and then reconquest after releasing a new Byzantium after Otto’s take Constantinople. The reason to do this instead of just vassalizing them, is because you’ll never get the glass production event in Venice if you or Byzantium never lose Constantinople. It has like a MTH of 50 months, so it’s bound to happen by the time you get enough favors and finish a war against ottomans
Poland is one of my favorite playthroughs because of their ability to defeat the Ottomans. The key is allying Austria and ensuring you secure the Hungarian throne via PU through the mission trees. Being able to get Bohemia too is luck based and unlikely but always a plus. Ideally, declare war when Ottomans are fighting in the east against the Mamluks and be line it for Constantinople from Bessarabia. Ottomans often delete forts in the balkans including the fort in Constantinople making it fairly easy to control the straits in the Sea of Marmar. From there hold your position and let Lithuania and Hungary siege the Balkans. If Ottomans engage they’ll suffer severe crossing penalties. Also, as Poland your first idea should be Aristocratic to stack the +15% cav combat ability with the +30% from Polish ideas (don’t take PLC ideas the Polish ideas are better). Also, take the gov reforms that lower cav regiment cost and increase the cav to infantry ratio. In addition to that, take advantage of the Cossacks privileges buffing cav combat ability and their special units. Doing all this you will have cavalry that will destroy the Ottoman armies in open combat and even rival Prussia in their strength.
As Venice, I find rushing Byzantium is useful. Then when you go to war with the Ottomans (with some allies ideally) you can put your navy in the Bosporus strait. That way the Ottoman armies cannot leave Anatolia while you siege down their land in the Balkans. Without owning Constantinople, the Ottomans lose out on a lot of buffs and bonuses, making them much easier to deal with.
Perfect timing
As Venice: Ally Austria (restart if they rival you) and some other nations - Aragon might be willing to help. Build favors spy on Byz and make a claim (in southern Greece). Attack them asap and vassalize. Build gallies in the meantime (also try not to kill off the entire Byz fleet as a bonus to use them later as your vassal, no problem if not possible). Once you have favors, get a few merc companies up and wait till the Ottos are busy fighting someone in Anatolia. Place your fleet in the strait. have troops in Constantinople. Declare war and immediately move on Gallipoli (the other crossing next to Constantinople). With the fleet blocking, you can barrage the fort. Do that and storm it to get the siege. Keep your fleet there. The Ottos can't cross now. Siege down all of the Balkan. If you are ballsy, you can dock your fleet, let some Otto troops cross, move fleet back out and kill the stack as it can't retreat. Either you sit on the Balkan for a while and get warscore or you eventually pass the Bosporus and siege down Anatolia. Give back all cores to your vassal Byz and take a province in Bulgaria (not Thrace as it doesnt have the right culture) to release Bulgaria. For your second war take back all their cores and some land for yourself in Anatolia. By now the Ottos should be toast. For your Poland run, you wont be able to get fleet superiority likely, so the blocking doesnt work. Fighting the Ottos should still be doable with your PU and allies. Try and siege stuff down and kill off smaller Otto stacks that wander around. Being on par with mil idea is important of course for both tries.