1870 |
| Marx to Engels. 20 July | 3 |
| Engels to Marx. 22 July | 6 |
| Marx to Eugen Oswald. 26 July | 9 |
| Marx to Engels. 28 July | 10 |
| Marx to Paul and Laura Lafargue.
28 July | 12 |
| Marx to Engels. 29 July | 15 |
| Marx to Wilhelm Liebknecht.
29 July | 16 |
| Engels to Marx. 31 July | 17 |
| Marx to Engels. 1 August | 22 |
| Marx to Johann Philipp Becker.
2 August | 24 |
| Marx to Eugen Oswald. 2 August | 28 |
| Engels to Marx. 3 August | 29 |
| Marx to Engels. 3 August | 30 |
| Marx to Eugen Oswald. 3 August | 34 |
| Marx to Engels. 4 August | 34 |
| Engels to Marx. 5 August | 35 |
| Marx to Eugen Oswald. 5 August | 36 |
| Marx to Hermann Jung. 6 August | 36 |
| Marx to Eugen Oswald. 7 August | 37 |
| Marx to Engels. 8 August | 38 |
| Engels to Marx. 10 August | 41 |
| Marx to Engels. 12 August | 43 |
| Marx to Hermann Jung. 12 August | 44; |
| Marx to Engels. 15 August | 44 |
| Engels to Marx. 15 August | 45 |
| Engels to Jenny Marx. 15 August | 49 |
| Marx to Engels. 17 August | 50 |
| Engels to Marx. 20 August | 52 |
| Marx to Engels. 22 August | 54 |
| Marx to Engels. 30 August | 55 |
| Marx to Friedrich Adolph Sorge. 1 September | 56 |
| Marx to Engels. 2 September | 58 |
| Marx to Sigfried Meyer. 2 September | 60 |
| Engels to Marx. 4 September | 61 |
| Marx to Eugen Oswald. 4 September | 64 |
| Marx to Engels. 6 September | 64 |
| Engels to Marx. 7 September | 66 |
| Marx to Engels. 10 September | 69 |
| Engels to Marx. 12 September | 71 |
| Marx to Edward Spencer Beesly.
12 September | 73 |
| Engels to Marx. 13 September | 75 |
| Marx to Engels. 14 September | 76 |
| Marx to Johann Philipp Becker.
14 September | 78 |
| Marx to Cesar De Paepe. 14
September | 79 |
| Marx to Ludwig Kugelmann. 14
September | 81 |
| Marx to Eugen Oswald. 14 September | 82 |
| Marx to Johann Philipp Becker.
15 September | 83 |
| Marx to Engels. 16 September | 84 |
| Marx to Edward Spencer Beesly. 16 September | 84 |
| Marx to Eugen Oswald. 23 September | 87 |
| Marx to Edward Spencer Beesly. 19 October | 88 |
| Marx to Peter Imandt. 11 November | 89 |
| Marx to the Dutch and Flemish
Internationals. Between 5 and 9 December | 91 |
| Marx to Ludwig Kugelmann 13 December | 91 |
| Engels to Friederick Greenwood. 17 December | 95 |
| Engels to Natalie Liebknecht. 19 December | 95 |
1871 |
| Marx to Natalie Liebknecht. 13 January | 97 |
| Marx to Hermann Jung. 18 January | 98 |
| Marx to C. Julian Harney. 21
January | 100 |
| Marx to Sigfrid Meyer. 21 January | 101 |
| Marx to Friedrich Adolph Sorge.
21 January | 106 |
| Marx to Johann Jacoby. 4 February | 107 |
| Marx to Ludwig Kugelmann. 4
February | 108 |
| Marx to Paul Lafargue. 4 February | 112 |
| Marx to Pyotr Lavrov. 27 February | 115 |
| Marx to Natalie Liebknecht.
2 March | 115 |
| Engels to Karl Klein and Friedrich
Moll. 10 March | 117 |
| Engels to Rudolf Engels. 10 March | 119 |
| Marx to Paul Lafargue. 23 March | 121 |
| Marx to Peter Imandt. 30 March | 124 |
| Engels to Philippe Coenen. 5 April | 125 |
| Engels to Wilhelm Liebknecht. 5 April | 127 |
| Marx to Wilhelm Liebknecht. 6 April | 127 |
| Marx to Wilhelm Liebknecht. Around 10 April | 130 |
| Marx to Ludwig Kugelmann. 12 April | 131 |
| Marx to Wilhelm Liebknecht. 13 April | 135 |
| Engels to Wilhelm Liebknecht.
13 April | 136 |
| Marx to Ludwig Kugelmann. 17 April | 136 |
| Engels to Wilhelm Liebknecht. 20 April | 137 |
| Engels to Francisco Mora. Around 20 April | 139 |
| Marx to Friedrich Adolph Sorge. Around 20 April | 140 |
| Marx to Leo Frankel. Around 26 April | 141 |
| Engels to Ludwig Kugelmann. 28 April | 142 |
| Marx to Wilhelm Liebknecht. 4 May | 144 |
| Engels to Wilhelm Liebknecht. 4 May | 145 |
| Marx to Wilhelm Liebknecht. 5 May | 146 |
| Engels to Hermann Jung. 10 May | 147 |
| Marx to Leo Frankel and Louis Eugene Varlin. 13 May | 148 |
| Marx to Edward Spencer Beesly. 12 June | 150 |
| Marx to Nikolai Danielson. 13 June | 152 |
| Marx to His Daughters Jenny, Laura and Eleanor. 13 June | 153 |
| Engels to Elisabeth Engels. 16 June | 154 |
| Marx to Ludwig Kugelmann. 18 June | 157 |
| Marx to an Unknown Addressee. 19 June | 158 |
| Engels to Wilhelm Liebknecht. 22 June | 159 |
| Engels to Carlo Cafiero. 1-3 July | 161 |
| Engels to Wilhelm Liebknecht. 10 July | 166 |
| Marx to Leon Bigot. 11 July | 167 |
| Marx to Pyotr Lavrov. 12 July | 168 |
| Marx to A. O. Rutson. 12 July | 169 |
| Engels to Carlo Cafiero. 16 July | 170 |
| Marx to Eugen Oswald. 21 July | 174 |
| Marx to Nikolai Danielson. 22 July | 174 |
| Marx to Eugen Oswald. 24 July | 175 |
| Marx to Charles Caron. 26 July | 176 |
| Marx to Ludwig Kugelmann. 27 July | 176 |
| Engels to Wilhelm Liebknecht. Not later than 27 July | 177 |
| Marx to Nikolai Utin. 27 July | 178 |
| Engels to Carlo Cafiero. 28 July | 180 |
| Marx to Adolphe Hubert. 28 July | 188 |
| Engels to the Mother Superior of the Convent of the Sisters of Providence in Hampstead. Early August | 189 |
| Engels to Philippe Coenen. 4 August | 190 |
| Engels to Pyotr Lavrov. 9 August | 192 |
| Marx to Theodor Koll. 10 August | 194 |
| Marx to Adolphe Hubert. 10 August | 195 |
| Marx to Hermann lung. 14 August | 197 |
| Marx to Adolphe Hubert. Not before 14 August | 198 |
| Engels to Wilhelm Liebknecht. Mid-August | 199 |
| Engels to Marx. 18 August | 200 |
| Marx to Engels. 19 August | 201 |
| Marx to Engels. 21 August | 202 |
| Engels to Marx. 23 August | 202 |
| Marx to Engels. 24 August | 204 |
| Marx to Friedrich Bolte. 25 August | 204 |
| Marx to Jenny Marx. 25 August | 206 |
| Marx to Hermann Meyer. Around 25 August | 208 |
| Marx to Moncure Daniel Conway. 29 August | 209 |
| Engels to Pyotr Lavrov. 3 September | 210 |
| Marx to Friedrich Adolph Sorge. 5 September | 211 |
| Marx to Collet Dobson Collet. 6 September | 211 |
| Marx to Engels. 8 September | 213 |
| Engels to Miller & Richard. After 9 September | 214 |
| Engels to Wilhelm Liebknecht. 11 September | 215 |
| Marx to Friedrich Adolph Sorge. 12 September | 217 |
| Engels to Pyotr Lavrov. 12 September | 218 |
| Marx to Hermann Jung. 13 September | 219 |
| Marx to Adolphe Hubert. 15 September | 219 |
| Marx to Jenny Marx. 23 September | 220 |
| Marx to Gustav Kwasniewski. 29 September | 221 |
| Engels to Pyotr Lavrov. 5 October | 222 |
| Marx to Hermann Jung. 11 October | 223 |
| Marx to Hermann Jung. 13 October | 224 |
| 14S. Marx to John Hales. 14 October | 225 |
| Marx to Edward Spencer Beesly. 19 October | 226 |
| Marx to Hermann Jung. 19 October | 226 |
| Marx to Hermann lung. 20 October | 227 |
| Engels to Elisabeth Engels. 21 October | 228 |
| Marx to Edouard Vaillant. 22 October | 230 |
| Marx to Hermann Jung. Around 25 October | 231 |
| Marx to Hermann Jung. End of October | 232 |
| Engels to Wilhelm Liebknecht. 4 November | 232 |
| Marx to Hermann Jung. 4 November | :235 |
| 15S. Marx to Friedrich Adolph Sorge. 6 November | 236 |
| Marx to Ferdinand Jozewicz. 6 November | 237 |
| Marx to Nikolai Danielson. 9 November | 2S8 |
| Marx to Friedrich Adolph Sorge. 9 November | 241 |
| Marx to Ludwig Kugelmann. 9 November | 243 |
| Marx to Carl Speyer. 10 November | 243 |
| Engels to Theodor Cuno. 13 November | 245 |
| Marx to Hermann Jung. 16 November | 246 |
| Marx to Wilhelm Liebknecht. 17 November | 247 |
| Marx to Julius Johannard. 18 November | 248 |
| 16S. Marx to Hermann Jung. 18 November | 249 |
| Marx to Adolphe Hubert. 22 November | 250 |
| Marx to Friedrich Bolte. 23 November | 251 |
| Engels to Carmelo Palladino. 23 November | 259 |
| Marx to Cesar De Paepe. 24 November | 262 |
| Marx to Laura and Paul Lafargue. 24-25 November | 265 |
| Engels to Paul Lafargue. 25 November | 271 |
| Marx to Juliusz Balaszewicz-Potocki. 25 November | 272 |
| Marx to Juliusz Balaszewicz-Potocki. 29 November | 273 |
| Marx to Friedrich Adolph Sorge. 29 November | 273 |
| 17S. Engels to Pyotr Lavrov. 29 November | 275 |
| Engels to Paul Lafargue. 9 December | 277 |
| Engels to Wilhelm Liebknecht. 15 December | 279 |
| Marx to Laura Lafargue. 18 December | 283 |
| Engels to Paul Lafargue. 30 December | 284 |
1872 |
| Engels to Wilhelm Liebknecht. 2 January | 288 |
| Engels to Wilhelm Liebknecht. 3 January | 290 |
| Marx to Maltman Barry. 7 January | 290 |
| Engels to Carlo Terzaghi. First Version. After 6 January | 291 |
| Second Version. 14-15 January | 294 |
| Engels to Wilhelm Liebknecht. 18 January | 296 |
| Engels to Pyotr Lavrov. 19 January | 300 |
| Engels to Paul Lafargue. 19 January | 301 |
| Marx to Hermann Jung. 19 January | 305 |
| Engels to Theodor Cuno. 24 January | 305 |
| Engels to Carlo Terzaghi. 29 January | 312 |
| Marx to Ferdinand Jozewicz. 1 February | 314 |
| Marx to Hermann Jung. 1 February | 315 |
| Marx to Mauriee Laehatre and
Juste Vernouillet. 9. February | 316 |
| Marx to Adolphe Hubert. 12 February | 317 |
| Marx to Asher & Co. 13 February | 318 |
| Engels to Wilhelm Liebknecht. 15 February | 318 |
| Engels to Johann Philipp Becker. 16 February | 321 |
| Engels to Giuseppe Benedetti. 18 February | 323 |
| Engels to William Burrs. 22 February | 324 |
| Marx to Ferdinand Jozewiez. 24 February | 325 |
| Marx to Hermann Jung. 26 February | 326 |
| Marx to Laura Lafargue. 28 February | 327 |
| Engels to Sigismund Borkheim. Early March | 329 |
| Engels to Louis Pio. 7 March | 329 |
| Marx to Hermann Jung. 7 March | 333 |
| Marx to Friedrich Adolph Sorge. 8 March | 333 |
| Marx to Emile Eudes. 9 March | 335 |
| Engels to Paul Lafargue. 11
March | 336 |
| Engels to Laura Lafargue.
11 March | 338 |
| Engels to Louis Pio. Mid-March | 340 |
| Marx to Friedrich Adolph Sorge.
15 March | 341 |
| Engels to Friedrich Adolph
Sorge. 17 March | 342 |
| Marx to Maurice Lachatre.
18 March | 344 |
| Engels to Cesare Bert. 21
March | 345 |
| Marx to Paul Lafargue. 21
March | 346 |
| Engels to Carlo Terzaghi.
21 March | 352 |
| Marx to Edouard Vaillant.
4 April | 353 |
| Engels to Cennaro Bovio. 16
April | 354 |
| Engels to Theodor Cuno. 22-23
April | 356 |
| Engels to Wilhelm Liebknecht.
23 April | 360 |
| Marx to Johann Georg Eccarius.
3 May | 363 |
| Engels to Wilhelm Liebknecht.
7 May | 364 |
| Engels to Theodor Cuno. 7-8
May | 367 |
| Engels to Johann Philipp Becker.
9 May | 372 |
| Engels to Wilhelm Liebknecht.
15-22 May | 373 |
| Marx to Friedrich Adolph Sorge.
23 May | 377 |
| Marx to Edouard Vaillant.
24 May | 378 |
| Marx to Friedrich Adolph Sorge.
27 May | 379 |
| Engels to Wilhelm Liebknecht.
27-28 May | 380 |
| Marx to Nikolai Danielson. 28 May | 385 |
| Marx to Cesar De Paepe. 28
May | 386 |
| Marx to Friedrich Adolph Sorge.
29 May | 388 |
| Engels to Wilhelm Liebknecht.
5-6 June | 389 |
| Engels to. Molesworth. After
5 June | 391 |
| Engels to Cesare Bert. 7 June | 391 |
| Engels to Theodor Cuno. 10
June | 393 |
| Engels to Johann Philipp Becker.
14 June | 395 |
| Engels to Carlo Cafiero. 14
June | 397 |
| Marx to Friedrich Adolph Sorge.
21 June | 398 |
| Marx to Octave van Suetendael.
21 June | 400 |
| Engels to Adolf Hepner. 2
July | 403 |
| Engels to Th. Smart &
Co. After 3 July | 406 |
| Engels to Theodor Cuno. 5
July | 407 |
| Marx to Ludwig Kugelmann.
9 July | .....409 |
| Engels to Adolf Hepner. 9
July | 410 |
| Engels to Ugo Bartorelli.
18 July | 411 |
| Marx to Ludwig Kugelmann.
23 July | 412 |
| Marx to Ludwig Kugelmann.
29 July | 413 |
| Marx to Hermann Jung. End
of July | 413 |
| Engels to Adolf Hepner. 4
August | 414 |
| Engels to Theodor Cuno. 4
August | 416 |
| Engels to Johann Philipp Becker.
5 August | 418 |
| Engels to Walery Wroblewski.
7 August | 421 |
| Marx to Nikolai Danielson. 15 August | 421 |
| Marx to Juste Vernouillet.
15 August | 423 |
| Engels to E. Glaser de Willebrord.
19 August | 424 |
| Engels to Wilhelm Liebknecht.
24 August | 425 |
| Marx to Ludwig Kugelmann.
26 August | 426 |
| 256 Engels to Hermann Jung. Early
September | 427 |
| Engels to Maltman Barry. 15
September | 428 |
| Engels to Friedrich Adolph
Sorge. 21 September | 429 |
| Engels to Hermann Jung. 1
October | 434 |
| Marx to P. van der Willigen.
4 October | 434 |
| Engels to Friedrich Adolph
Sorge. 5 October | 435 |
| Marx to Maurice Lachatre.
12 October | 437 |
| Marx to Hermann Jung. 14 October | 439 |
| Engels to Friedrich Lessner.
16 October | 440 |
| Engels to Theodor Cuno. 29
October | 441 |
| Engels to Jenny Longuet. 30
October | 442 |
| Engels to Friedrich Adolph
Sorge. 2 November | 444 |
| Engels to Friedrich Adolph
Sorge. 16 November | 446 |
| Engels to Jenny Longuet. 19
November | 451 |
| Marx to Nikolai Danielson.
25 November | 452 |
| Engels to Friedrich Adolph
Sorge. 7 December | 453 |
| Marx to Nikolai Danielson. 12 December | 455 |
| Engels to Friedrich Adolph
Sorge. 14 December | 458 |
| Marx to Friedrich Adolph Sorge.
21 December | 459 |
| Marx to William Riley. 23
December | 461 |
| Engels to Adolf Hepner. 30
December | 462 |
1873 |
| Engels to Friedrich Adolph
Sorge. 4 January | 464 |
| Engels to Rudolf Seiffert.
Between 15 and 20 January | 468 |
| Marx to Nikolai Danielson. 18 January | 469 |
| Engels to Eugen Oswald. 29 January | 471 |
| Marx to Aristide Fanton. 1 February | 472 |
| Marx to Johann Philipp Becker. 11 February | 473 |
| Marx to Friedrich Bolte. 12 February | 474 |
| Engels to Wilhelm Liebknecht. 12 February | 477 |
| Engels to Maurice Lachatre. After 14 February | 478 |
| Engels to Natalie Liebknecht. 11 March | 479 |
| Engels to Eugen Oswald. 18 March | 480 |
| Engels to Friedrich Adolph Sorge. 20 March | 481 |
| Engels to Maurice Lachatre. After 21 March | 486 |
| Marx to Nikolai Danielson. 22 March | 487 |
| Engels to Friedrich Adolph Sorge. 22 March | 487 |
| Marx to Johann Philipp Becker. 7 April | 488 |
| Engels to Friedrich Adolph Sorge. 3 May | 490 |
| Marx to Maurice Lachatre. 12 May | 495 |
| Marx to Engels. 23 May | 495 |
| Marx to Hugo Heller. 23 May | 496 |
| Engels to Marx. 24 May | 497 |
| Marx to Engels. 25 May | 498 |
| Engels to Marx. 26 May | 499 |
| Engels to Marx. 30 May | 500 |
| Marx to Engels. 31 May | 504 |
| Engels to Friedrich Adolph Sorge. 14 June | 507 |
| Engels to August Bebel. 20 June | 513 |
| Engels to Walter Whitter. Not before 24 June | 515 |
| Engels to Ludwig Kugelmann. 1 July | 515 |
| Marx to Juste Vernouillet. 10 July | 517 |
| Engels to Friedrich Adolph Sorge. 26 July | 518 |
| Marx to Nikolai Danielson. 12 August | 522 |
| Marx to Engels. 29 August | 523 |
| Engels to Marx. 30 August | 525 |
| Marx to Engels. 30 August | 526 |
| Engels to Marx. 3 September | 527 |
| Marx to Benjamin Le Moussu. After 3 September | 529 |
| Marx to Engels. 9 September | 530 |
| Engels to John De Morgan. Around 18 September | 531 |
| Marx to Eugen Oswald. 20 September | 532 |
| Marx to Eugen Oswald. 24 September | 533 |
| Marx to Friedrich Adolph Sorge. 27 September | 534 |
| Engels to Friedrich Adolph Sorge. 25 November | 536 |
| Engels to Marx. 29 November | 539 |
| Marx to Engels. 30 November | 541 |
| Engels to Marx. 5 December | 544 |
| Marx to Engels. 7 December | 546 |
| Engels to Marx. 10 December | 548 |
| Marx to Engels. 11 December | 549 |
| Marx to Thomas Allsop. 23 December | 550 |
Appendices |
| Jenny Marx to Engels. 10 August
1870 | 555 |
| Eleanor Marx to Engels. 12 August
1870 | 557 |
| Jenny Marx to Engels. Around
18 August 1870 | 558 |
| Jenny Marx to Engels. Around
13 September 1870 | 559 |
| Jenny Marx to Peter Imandt.
Around 13 June 1871 | 561 |
| Jenny Marx (daughter) to Ludwig
Kugelmann. 3 October 1871 | 562 |
| Eleanor Marx to Aristide Barre.
10 October 1871 | 565 |
| Jenny Marx (daughter) to Ludwig
and Gertrud Kugelmann. 21-22 December 1871 | 565 |
| Eleanor Marx to Wilhelm Liebknecht.
29 December 1871 | 571 |
| Jenny Marx (daughter) to Ludwig
Kugelmann. 22 January 1872 | 573 |
| Eleanor Marx to Nikolai Danielson.
23 January 1872 | 575 |
| Wilhelm Liebknecht to Luigi
Stefanoni. 29 February 1872 | 577 |
| Jenny Marx (daughter) to Ludwig
Kugelmann. 3 May 1872 | 578 |
| Jenny Marx to Wilhelm Liebknecht.
26 May 1872 | 579 |
| Jenny Marx (daughter) to Ludwig
and Gertrud Kugelmann. .27 June 1872 | 582 |
| Jenny Marx-Longuet to Ludwig
and Gertrud Kugelmann. 23 December 1872 | 583 |
| Jenny Marx-Longuet to Ludwig
and Gertrud Kugelmann. 12 May 1873 | 585 |
| Charles Longuet to Hugo Heller.
23 June 1873 | 587 |
Notes and Indexes |
| Notes | 591 |
| Name Index | 682 |
| Index of Quoted and Mentioned Literature | 725 |
| Index of Periodicals | 758 |
| Subject Index | 769 |
Illustrations |
| A page from Marx's letter to Sigfrid
Meyer of 21 January 1871 | 103 |
| Marx's letter to Ludwig Kugelmann
of 12 April 1871 | 133-34 |
| A page from Marx's letter to Friedrich
Bolte of 23 November 1871 | 253 |
| Friedrich Sorge, August Bebel,
Theodor Cuno, Pyotr Lavrov, Leo Frankel, Edward Beesly | 368-69 |
| First page of Engels' letter to
Maurice Lachatre written in March (after the 21st) 1873; Maurice Lachatre,
Adolf Hepner | 486-87 |
| First page of Engels' letter to
Marx of 30 May 1873 | 501 |