Al-Shabaab formed an alliance with the Islamic Courts Union in 2006 to counter the alliance of 10 warlords formed by the CIA that February but they didn't ever see eye to eye.
Source: Inside Al-Shabaab: The Secret History of Al-Qaeda’s Most Powerful Ally by Harun Maruf
I think this is noteworthy because some people reminisce about the ICU days and what could have been. However, I think this makes it clear that the ICU was never going to last - Ethiopian invasion or no Ethiopian invasion. Al-Shabaab were intent on replicating Taliban ruled Afghanistan at all costs.
This also shows how uncompromising they are in their views. If they couldn't get along with the ICU, how can they ever negotiate with the FGS?
Source: Inside Al-Shabaab: The Secret History of Al-Qaeda’s Most Powerful Ally by Harun Maruf
I think this is noteworthy because some people reminisce about the ICU days and what could have been. However, I think this makes it clear that the ICU was never going to last - Ethiopian invasion or no Ethiopian invasion. Al-Shabaab were intent on replicating Taliban ruled Afghanistan at all costs.
This also shows how uncompromising they are in their views. If they couldn't get along with the ICU, how can they ever negotiate with the FGS?