The enemy’s method of operation, except for a brief determined stand near and in Seoul, consisted of moderate to strong delaying actions. The first reaction following the initial disorganization at Inchon was an attempt to contain our advance until such time as sufficient reinforcements could arrive to warrant initiating a counteroffensive. In view of the scarcity of reinforcements and our own rapid advances, this never materialized.
The Order of Battle of the units which opposed the advance of the Division from the time of the landing at Inchon until the capture of Uijongbu, north of Seoul, is given below:
| Unit | POWs captured |
Area of employment | Strength | Remarks |
| 226th Marine Regt | 183 | Inchon | 2,000 | In the Inchon area prior to the landing. Newly conscripted and poorly trained. |
| 918th (Coast) Art Regt (Elements). | 2(?) | do | 200 | In the Inchon area prior to the landing. 8 76mm guns. Wiped out or scattered by naval and air bombardment. |
| Air Force Division | 91 | Kimpo Airfield | 485 | When out troops approached the airfield area part of the personnel from this unit withdrew across the Han River. |
| 42d Mech (Tank) Regt | 11 | Between Inchon and Seoul. | 500 | Arrived in Seoul from Sinuiju in early Sept. 18 T-34 tanks. |
| 107th Security Regt | 270 | Kimpo Area | 2,500 | In the Kimpo area when we landed. A quasi-military organization. |
| Rehabilitation Bn (Special Cultural) Bn. | 16 | West of Yongdungpo. | 230 | This unit was organized on 19 Sept and contained NK prisoners serving sentence in Seoul. Officers were also former prisoners. Most were serving sentence for desertion. |
| 3d Regt, 9th Rifle Div | 23 | Yongdungpo | 2,000 | Remainder of the division on the southern front. |
| 25th Inf Brig | 179 | Seoul | 4,000- 5,000 |
Arrived from Chorwon on 20 Sept. An excellent unit which opposed the 5th Marines on the western approaches to Seoul. |
| 18th Rifle Div | 301 | Seoul and Yongdungpo. | 8,000- 10,000 |
Arrived from Chorwon in mid-August. Known as the Seoul Defense Division. It was the only unit of division strength in the area. |
| 43d Tank Regt | 56 | Seoul | 500 | Arrived from Wonsan 23 Sept. 10–15 T-34 tanks. |
| 19th AA Regt | 5 | do | 1,200 | In Seoul when we landed. 37mm, 85mm, and 12.7mm AT guns. |
| 76th Ind Regt, 42d Div | 218 | do | 3,000 | Arrived from Wonsan after 17 Sept. Was opposite the 5th Marines but withdrew from Seoul almost intact. |
| 78th Ind Regt | 528 | do | 2,000 | Arrived from Sariwon on 20 Sept. Opposed the 5th and 1st Marines. Put up stubborn defense and suffered heavy losses. |
| 513th Art Regt | 33 | do | 1,500 | Arrived from Chorwon on 23 Sept. 1 76mm and 5 45mm guns. Most of the regiment served as infantry. |
| 10th Railroad Regt. | 17 | do | 900 | In Seoul when we landed. Its mission was to maintain the security of the railroad lines and keep them in operation. It participated in the defense of Seoul. |
| 31st Rifle Div/or Seoul City Regt. | 345 | do | 3,600 | In Seoul when we landed. Formed as a division on 20 Sept by an amalgamation of units in Seoul. Participated in the defense of Seoul and delayed our advance north to Uijongbu. |
| 36th Bn, 111th Security Regt | 32 | do | 750 | In Seoul when we landed. |
| 2d Regt 17th Rifle Div (Reinforced) | 41 | Seoul- Uijongbu | 3,500 | Withdrawn from the southern front after the landing at Inchon. |
| 75th Ind Regt. | 16 | Uijongbu | 2,000 | Arrived from Hamhung on 30 Sept. Used as a covering force to cover the withdrawal through Uijongbu. |
| 27th Inf Brig. | 123 | Suyuhyon | 5,000 | Arrived from Kumchon on 1 Oct. Withdrew in the face of the advance of the 5th Marines to Suyuhyon, 17 miles northwest of Seoul. |
| Total Enemy Strength | 44,380 | |||
485 Unknown.
A total of 428 prisoners interrogated did not know enough of their own units to be further identified. Approximately 1,000 prisoners were not interrogated due to the heavy initial influx.
Prisoners were captured from some 24 units not listed above, but the number of prisoners captured from individual units was not sufficient to accept the presence of the unit. Further, many of these POWs were deserters or wounded from the southern front.
The identification, by date, of North Korean units opposing the 1st Marine Division is indicated below:
| 15 September | 226th Ind Marine Regt (2 Bns). | 2,000 defending Wolmi-do and Inchon |
| 918th Art Regt (2 Cos) | 200 defending Wolmi-do | |
| 16 September | 18th Rifle Div (Opposing 1st Marines) | 300 POWs and 1,350 enemy casualties for the first two days, 15 and 16 Sep |
| 17 September | 42d Mech (Tank) Regt (Opposing 1st Marines) | Lost 14 T-34 tanks |
| 107th Security Regt (Kimpo) (Opposing KMC & 5th Marines) | 400 POWs and 350 enemy casualties | |
| 18 September | NK Air Force EngBn (Opposing 5th Marines) | 197 POWs and 450 enemy casualties |
| 19 September | No additional identifications on fronts of 1st and 5th Marines | 126 POWs and 600 enemy casualties |
| 20 September | 78th Ind Regt (Opposing 5th Marines) No additional identifications on front of 1st Marines | 326 POWs and 600 enemy casualties |
| 21 September | No additional identifications | 355 POWs and 1,350 enemy casualties |
| 22 September | Rehabilitation Bn (Opposing 1st Marines). | 395 POWs and 1,250 casualties |
| 25th Inf Brig (Opposing 5th Marines) | ||
| 31st Rifle Div (Seoul City Regt) (Opposing 5th Marines) | ||
| 23 September | No additional identifications | 169 POWs and 900 casualties |
| 24 September | do | 67 POWs and 950 casualties |
| 25 September | do | 142 POWs and 1,750 casualties |
| 26 September | 76th Ind Regt | 407 POWs and 950 casualties |
| 43d Tank Regt | ||
| 19th AA Regt | ||
| 513th Art Regt | ||
| 17th Rifle Div (Opposing 1st & 5th Marines) | ||
| 27 September | No additional identifications | 139 POWs and 1,252 casualties |
| 28 September | do | 206 POWs and 332 casualties |
| 29 September | do | 507 POWs and 102 casualties |
| 30 September | do | 328 POWs and 305 casualties |
| 1 October | do | 124 POWs and 75 casualties |
| 2 October | 27th Inf Brig (Opposing 5th Marines) | 82 POWs and 350 casualties |
| 75th Ind Regt (Opposing 7th Marines) | ||
| 3 October | No additional identifications | 103 POWs and 800 casualties |
| 4 October | do | 118 POWs |
| 5 October | do | 57 POWs |
| 6 October | do | 144 POWs |
In the above tabulation, a unit is shown only for the first day upon which it was identified by the capture of prisoners. In the cases of most of the units there were recurring captures of prisoners.