Examples of How to Have a 2nd Layer of Convoy Defense

In theory, you could have three battles when attacking/defending convoys. This is how one might bring it about. Note that for this to happen lots of legal but improbable things have to line up just right. As a practical matter, one and rarely two battles is all that will happen.

Typical Defense

The raider has a moderate sized squadron- CWL, 3xCW, DWS, 2xDW. They start in hex A31 (normal hex), and move to A32 (trade route), and have plotted to move to A33 as well.
The defender has a squadron in hex A32 with orders to intercept (technically interdict) enemy forces (either they started there or entered the hex on the same segment as the raider).
The first battle that could happen would be between the raiding and defending SQs (the raider could use a BM RX to avoid this). If the raider wins, they could then search the hex for a convoy. That convoy could itself be defended by ships assigned to convoy defense and/or normal defenses via E6.0.

The first battle might not happen if the raider encounters, for example, a DN SQ. The raid might not happen if the raider loses the first battle. The raid might be rolled for, and if the responding forces are too large (or the raider has hit their DI), it doesn't get fought (raider leaves before they engage). Note that the defended convoy's allocation could impact responding forces to other raids on the same segment (see below).

If the raider defeats the defender and defeats the defended convoy it could proceed to A33.

Very In the Weeds Defense

Assume the raider fights and wins against the defending squadron as above. They then proceed to raid the hex. Because they took substantial damage, they won't fight a defended convoy, only an undefended one. Assume they find a convoy that is in fact defended. They don't actually engage the convoy, but the responding forces are marked as responding for the segment.

If only one raided convoy was defended on this segment, then the defender will have the two AuxCVs, plus the 4xCA and 8xFF.

If the raider did three other raids on the same segment (and those convoys were defended), the responding forces would be smaller- 1xCA and 2xFF (plus the AuxCVL shows up somewhere). These smaller forces are easier to beat (and cause less damage before giving up), and might be worth the damage to the CWL SQ. This is why one might do lots of raids in a single segment, and accept that some will find stuff but not actually attack what is found.

All the Edge Cases

Assume the Attacker (A) enters a hex and intends to convoy raid against the Defender (D) who is already there (or entered on the same segment). Assume that A and D both have suitable military forces in the raided hex and that, if A attempts to find a convoy, they'll succeed. Also assume that neither side has met their DI before this process starts (see D's situation in 1.4 however)..

This is what the two parties can do:

• 1.0) Various steps can be taken to "force" (or avoid) battle (a LA can also influence things, but with the rest of this documented, how the LA works should be easy to figure out)
• 1.1) A may use a BM to avoid the battle (if D used a BN however, the battle still would happen)
• 1.2) D may Interdict A (if A uses a BM, and D doesn't have a BN available to respond with,they would avoid this battle). If A wins the battle, they can proceed to the later steps. If D wins, A can't raid (nor continue moving).
• 1.3) Normally, D could use a BN to force a battle, but interdiction allows them to do the same thing. This is included not because it happens but to show why it isn't needed.
• 1.4) If D has already met its DI, it can't fight in the 1.x step unless A uses BN to force the issue (but see F2.28).
• 2.0) D may attempt to defend the convoy (without the convoy being present- this is akin to an F&E "approach battle"). This could result in a 2nd battle between A and D (if A won the previous battle). If A loses this battle, they can't move out of the hex nor raid. If A wins the battle, then...
• 3.0) If A finds a convoy (this example assumes this happens, but it isn't a sure thing), then ...
  Generate the defending forces (if any) from responding Convoy Duty forces (F5.50 through F5.61) plus any "defended convoy" forces from rules E6.0 and E7.0. A will see these forces and might opt to decline to continue the raid (3xF5 facing a couple of police ships plus an AuxSCS might decide to hunt easier targets).
• 3.1) Having seen the responders and knowing if A plans to fight them, D may choose to fight with the convoy forces (this would include the F-L/F-S of a typical convoy plus the extra forces (if any) noted above. This is a possible 3rd battle between A and D in this hex and segment.
• 3.2) D may choose to not defend the convoy. Note that the forces added to the convoy via F5.50-F5.61 as well as E6.0 and E7.0 would still be in the convoy (and probably lost without D showing up).

Still more edge cases and nits:

• A could use a Bypass Movement RX (C2.55) to bypass the 2.0 battle, but only if they didn't use one already (C2.55b limits you to avoiding one battle per turn this way).
• DI thresholds may short circuit A from engaging in later steps.
• Repairs via (D3.10), (D3.20), and/or (D3.30) might get A back under its DI, but as soon as it leaves a battle due to hitting DI, it can no longer start a battle this turn (even with a Bottleneck (C2.50)).
• DI thresholds may short circuit D from engaging in steps 1 and/or 2
• Repair via (D3.10), (D3.20), and/or (D3.30) could enable D to repair enough damage to get it under its DI and thus fight in later battles in this sequence. Example: It just goes over its DI and leaves a battle from the "1" sequence, above. Repairs bring it under its DI, so it could perform the "2" battle.
• If D has met DI limits, it may still opt to engages in the 3.1 battle- Because the convoy is a defendable object (along with a planet or base- see C1.80), D may, even if its DI has been met previously, use option 3.1. Note that this combined force might still be over its DI, and those forces able to use disengagement would so so after round 1 (they'd announce before round 1).